Best LLM Models in 2025: A Practical Guide

Model choice should follow the job. As of July 2025, the landscape has consolidated around a few standout models per category. GreatChat routes automatically via OpenRouter, but you can override per chat. Below are the models worth knowing — with context windows, strengths, and when to use each.

General chat & research (flagship)

• Claude 4 Sonnet (200k ctx) — Best all-rounder: reasoning, tool use, long-context, writing. Default for most GreatChat tasks.
• GPT-4o (128k ctx) — Strong multimodal (text + image in/out), fast, great instruction following. Good for quick turns.
• Gemini 2.5 Pro (2M ctx) — Massive context for whole-repo analysis, long docs, video transcripts. Slower, but unmatched breadth.
• GPT-5 / GPT-5-mini (if released) — Watch for step-change in reasoning and tool use.

Coding & agentic work

• Claude 4 Opus — Best for complex refactors, multi-file edits, test generation.
• DeepSeek-Coder-V2 / V3 (open, 128k ctx) — Remarkable code quality, free/cheap via OpenRouter. Great for internal tools.
• Qwen 2.5-Coder (open, 128k ctx) – Strong across languages, good for fine-tuning.
• GPT-4o – Reliable for PR reviews, boilerplate, CI fixes.

Fast / cheap / high-volume

• Gemini 2.5 Flash — Sub-second latency, 1M ctx, very cheap. Ideal for classification, extraction, high-volume chat.
• Claude 4 Haiku — Fast, capable, 200k ctx. Great for tool-heavy loops.
• GPT-4o-mini — Solid generalist at fraction of 4o cost.
• Llama 3.3 70B / Nemotron 3 Ultra (open) — Strong open options via OpenRouter free tiers.

Long-context research (≥1M tokens)

• Gemini 2.5 Pro (2M) — Only model that reliably uses full 2M context.
• Gemini 2.5 Flash (1M) — 10x cheaper, 90% of Pro quality for retrieval tasks.
• Claude 4 Sonnet (200k) — Better reasoning per token, but hits limit sooner.

Image generation

• FLUX 1.1 Pro / Dev — Best overall quality, prompt adherence, text rendering.
• GPT-4o image (native) — Conversational editing, inpainting, consistent characters.
• Ideogram 2.0 — Best for typography, logos, graphic design.
• Recraft v3 — Vector output, style control, design workflows.
• Open: FLUX Schnell, SD 3.5 — Self-hostable, good for volume.

Video generation

• Runway Gen-3 Alpha — Best photorealism, camera control, 10s clips.
• Kling 1.6 — Strong motion, 10s, good prompt adherence.
• Luma Dream Machine 1.6 — Fast, good for ideation, 5s clips.
• Sora (if available) — 20s, strong physics, but limited access.
• Open: CogVideoX-5B, LTX-Video — Local inference possible.

Music / audio generation

• Suno v4 — Best full-song quality, vocals, structure.
• Udio 1.5 — Strong genre control, stems export.
• MusicGen (Meta) — Open, melody conditioning, 30s clips.
• AudioLDM 2 — Text-to-audio (SFX, ambience), open.

Open vs proprietary: practical routing

• Use proprietary (Claude 4, GPT-4o, Gemini 2.5) for: customer-facing assistants, tool-heavy agents, long-context reasoning, when you need reliability and support.
• Use open (DeepSeek, Qwen, Llama, FLUX, CogVideo) for: internal copilots, high-volume classification, fine-tuning, data-sensitive workloads, cost optimization.
• GreatChat default: Claude 4 Sonnet for chat/agents, Gemini 2.5 Flash for fast tasks, FLUX for images. Override per chat via model picker.

Reference dashboards: OpenRouter rankings, LMSYS Chatbot Arena, Open LLM Leaderboard. In GreatChat, pick the model per task while the interface and connections stay consistent.