In short
As of 2 November 2026 no single model leads everything: on Artificial Analysis's Intelligence Index, Claude Opus 5.5 (58), GPT-6 Astra (57), GPT-6.1 Sol (55) and Claude Sonnet 5.5 (54) form the top cluster, with Gemini 4 Argon (50) behind and open-weight models (Kimi K3.1 Pro, GLM-5.3, DeepSeek V4.1 Flash) lower but far cheaper. Price differs more than capability: list prices run from $0.15 to $50 per million tokens, so most teams cascade between tiers.
All figures below were read on 2026-11-02 from the vendor or tracker pages linked in each section. Index scores are the highest-scoring effort variant the tracker shows and change often; treat them as a snapshot, not a verdict.
#1. Frontier benchmarks, reasoning capabilities, and context windows
- Composite indexes: The Artificial Analysis leaderboard lists Claude Opus 5.5 at 58 (its best variant; lower effort settings score 35 to 52), GPT-6 Astra 57, GPT-6.1 Sol 55, Claude Sonnet 5.5 54, Gemini 4 Argon 50, Claude Fable 5.1 49, Kimi K3.1 Pro 46, and DeepSeek V4.1 Flash and GLM-5.3 32 each. On BenchLM (last verified 29 October 2026) Opus 5.5 scores 86.29 overall (rank 2) and GPT-6.1 Sol 85.27 (rank 4).
- Reasoning effort matters: The same model scores very differently by effort setting (Opus 5.5: 35 at low, 58 at max), so compare like with like.
- Context windows: Claude Fable 5.1, Opus 5.5 and Sonnet 5.5 each list a 1M-token context window and 128K max output. GPT-6 Astra and GPT-6.1 Sol list 1,050,000 tokens (OpenAI bills prompts above 272K input tokens at a higher rate). Gemini 4 Argon lists 1,048,576. Artificial Analysis also lists 1M for the open-weight models above.
#2. Enterprise stacks, coding, and complex workflows
For enterprise production, execution reliability, tool-harness compatibility and budget matter as much as raw capability. Published coding-benchmark numbers for these models could not be verified against a primary source on 2026-11-02, so none are quoted here; run your own evaluation on your repositories.
- Price ratio: Claude Sonnet 5.5 and GPT-6.1 Sol list at $2 input / $10 output per million tokens, one-fifth of the $10 / $50 charged for Claude Fable 5.1 and GPT-6 Astra.
- The routing pattern (a common design, not a vendor claim):
- Default workhorse: Claude Sonnet 5.5 or GPT-6.1 Sol ($2/$10).
- Escalation: Claude Opus 5.5 ($4/$20) when a cheaper model's output fails a check.
- Bulk batch: DeepSeek V4.1 Flash for classification and extraction (from $0.15/$0.60 off-peak; $0.30/$1.20 at peak hours).
#3. Open-weight contenders vs. proprietary frontier engines
The gap has narrowed in targeted domains. On the Artificial Analysis index the best open-weight entries listed above (Kimi K3.1 Pro, 46) sit below the top proprietary models (54 to 58) as of this snapshot.
| Category | Proprietary (Claude / GPT-6 / Gemini 4) | Open-weight (DeepSeek / Kimi / GLM) |
|---|---|---|
| Hosting | Vendor API or managed cloud (AWS, Google Cloud, Microsoft Foundry for Claude) | Self-hosted or third-party hosted, where weights are released |
| Data residency | Governed by vendor terms and data-processing agreements | Full control when self-hosted |
| Customization | Prompting, retrieval, vendor fine-tuning where offered | Weight access allows fine-tuning (for example LoRA) |
| Index score (AA, highest variant) | 49 to 58 | 32 to 46 |
| List price per 1M tokens (input/output) | $2/$10 to $10/$50 | DeepSeek V4.1 Flash from $0.15/$0.60 |
#4. Multimodal evaluation
- Do not trust synthetic scores alone: Document and chart extraction quality depends heavily on your own documents and parsing harness; test on a sample of your own files.
- Audio: Google's Gemini 4 Argon page states it accepts audio input but produces text output only, and does not support the Live API. Do not assume native speech-to-speech from the Gemini 4 Argon API.
- Inputs: Anthropic states all current Claude models accept text and image input and produce text output.
#5. Developer pricing and token limits
List prices per million tokens as published on 2026-11-02:
| Model | Input / Output | Source note |
|---|---|---|
| DeepSeek V4.1 Flash | $0.15 / $0.60 off-peak; $0.30 / $1.20 at peak | DeepSeek; peak is 01:00-04:00 and 06:00-10:00 UTC on weekdays |
| Claude Sonnet 5.5 | $2 / $10 | Anthropic |
| GPT-6.1 Sol | $2 / $10 | OpenAI |
| Gemini 4 Argon | $2 / $10 through 30 Nov 2026, then $4 / $20 from 1 Dec 2026 | |
| Claude Opus 5.5 | $4 / $20 | Anthropic |
| Claude Fable 5.1 | $10 / $50 | Anthropic |
| GPT-6 Astra | $10 / $50 | OpenAI |
Batch APIs are discounted (Anthropic and OpenAI both list 50% off), and cached input is far cheaper; check each page before budgeting.
#6. Architecture trends
Vendors disclose little about frontier architectures, so treat these as general trends rather than facts about specific models:
- Sparse Mixture-of-Experts: Open-weight reports such as the DeepSeek-V3 technical report describe MoE models that activate a small fraction of their parameters per token (37B of 671B in V3). Closed labs do not publish this for their frontier models.
- Reasoning-effort controls: APIs now expose an effort setting. Anthropic documents
effortlevels and adaptive thinking; Artificial Analysis lists scores per effort level. - Agentic post-training: Labs describe training models with tool use in execution environments; see each lab's model documentation for specifics.
#7. Autonomous agents and multi-step loops
- Harness sensitivity: Benchmark results can vary with the agent harness (terminal agent, IDE, or custom orchestration) as well as the model.
- Error recovery: Reading compiler or API errors and correcting course without human help is the practical test of agentic ability.
- Cost accumulation: Agents make many model calls per task, so list price compounds: at $2/$10 versus $10/$50, token cost per identical call is 80% lower, before differences in how many tokens each model uses (Artificial Analysis's cost-per-task figures show this does not always track list price).
#8. Safety and access controls
- Gated access: Anthropic lists Claude Mythos 5.1 as limited availability on its pricing page, priced like Fable. Press and aggregator reports tie the Mythos line to Project Glasswing, a vetted-partner programme for defensive security; the participant numbers reported vary by source and are not repeated here.
- Google's staged rollouts and any vendor-specific biosecurity or cyber guardrails on Claude Fable 5.1 were not verified against a primary source and are not described here.
- Compliance: Which export-control or regulatory regimes apply depends on the vendor, product and customer; check current law rather than relying on a summary.
#9. Quantitative research and data analysis
- Execute code: Text-only arithmetic and statistics can contain errors; have the model write and run code in a sandbox for anything numerical.
- Long inputs: A 1M-token window can hold a full 10-K, but verify retrieval with spot checks.
- Cross-checking: Having a second model from a different vendor review the first model's analysis is a cheap way to catch errors (our recommendation, not a measured result).
#10. Composite ranking snapshot
Ordered by Artificial Analysis Intelligence Index (highest variant listed, read 2026-11-02). Positions can change with every model release or re-run.
| Rank | Model | AA index | List price (in/out per 1M) | Deployment note (our view) |
|---|---|---|---|---|
| 1 | Claude Opus 5.5 | 58 | $4 / $20 | Escalation tier for hard engineering and reasoning |
| 2 | GPT-6 Astra | 57 | $10 / $50 | Highest-priced OpenAI tier |
| 3 | GPT-6.1 Sol | 55 | $2 / $10 | Strong score per dollar |
| 4 | Claude Sonnet 5.5 | 54 | $2 / $10 | Default workhorse |
| 5 | Gemini 4 Argon | 50 | $2 / $10 (rising 1 Dec 2026) | Google Cloud integration |
| 6 | Claude Fable 5.1 | 49 | $10 / $50 | Anthropic positions it for long-horizon agentic work |
| 7 | Kimi K3.1 Pro | 46 | not verified | Open-weight option |
| 8 | DeepSeek V4.1 Flash / GLM-5.3 | 32 / 32 | from $0.15 / $0.60 (DeepSeek) | Low-cost bulk work |
#Recommendation
For most engineering teams, a hybrid cascade is a sensible default: Claude Sonnet 5.5 or GPT-6.1 Sol as the primary driver, Claude Opus 5.5 for difficult cases, and DeepSeek V4.1 Flash for bulk extraction. Validate on your own tasks; index scores are not a substitute.
#Frequently asked questions
#What is the most capable AI model in 2026?
It depends on the benchmark. On Artificial Analysis's Intelligence Index, read on 2 November 2026, Claude Opus 5.5 scored highest at 58, followed by GPT-6 Astra at 57 and GPT-6.1 Sol at 55. Scores vary by reasoning-effort setting and change as trackers re-run evaluations, so check the live leaderboard.
#How much do the leading models cost per million tokens?
As of 2 November 2026: Claude Sonnet 5.5 and GPT-6.1 Sol are $2 input and $10 output; Claude Opus 5.5 is $4 and $20; Claude Fable 5.1 and GPT-6 Astra are $10 and $50. Gemini 4 Argon is $2 and $10 until 30 November 2026, then $4 and $20. Batch and caching discounts apply.
#How do test-time reasoning models work?
Instead of answering immediately, these models spend extra computation at inference generating intermediate reasoning before the final answer. Vendors expose this as an effort or thinking setting. Higher effort usually raises accuracy on hard problems but costs more tokens and time, as Artificial Analysis's per-effort scores for Claude Opus 5.5 show.
#Should enterprises choose open-weight or proprietary models?
Choose on data control versus capability and operating effort. Proprietary APIs currently score higher on Artificial Analysis's index (49 to 58 versus 32 to 46 for the open-weight models listed) and need no infrastructure. Open-weight models allow self-hosting, data residency and fine-tuning, and can be much cheaper for bulk tasks.
#Do all frontier models have million-token context windows?
The current Claude 5.x models, GPT-6 Astra, GPT-6.1 Sol and Gemini 4 Argon each list context windows of about 1M tokens in vendor documentation as of 2 November 2026. Output limits differ, and OpenAI charges more for prompts above 272K input tokens, so check long-context pricing.
#Does Gemini 4 Argon support speech-to-speech?
Not through the Gemini API as documented on 2 November 2026. Google's model page says it accepts audio input but outputs text only, and that the Live API is not supported. Check Google's page for changes before designing a voice product around it.
#Sources
- Artificial Analysis: model leaderboard and Intelligence Index (read 2026-11-02; page is undated).
- BenchLM leaderboard (last verified 29 October 2026 per the page).
- Anthropic: Models overview and Pricing.
- OpenAI: GPT-6 Astra model page and GPT-6.1 Sol model page.
- Google: Gemini 4 Argon model page and Gemini API pricing.
- DeepSeek API pricing.
- DeepSeek-AI. (2024). DeepSeek-V3 Technical Report. arXiv:2412.19437.
- DeepSeek-AI. (2025). DeepSeek-R1: Incentivizing Reasoning Capability in LLMs via Reinforcement Learning. arXiv:2501.12948.

