Should my chatbot use GPT-4-class models?

Probably not for every turn. Use a cheap model by default and escalate.

What’s a good latency target?

Under ~500ms TTFT feels snappy for chat. Measure in your region; our arena numbers are a relative signal.

How do I keep the bot on-policy?

RAG + system prompt + moderation + evals. Model choice is one layer.

Open-weight chatbots?

Viable if you can host and still hit latency. Compare open rows on cost and quality first.

Best LLM for chatbots — latency, cost and tone

Chatbots are latency- and cost-sensitive. Users feel 2 seconds. Finance feels 100M tokens a month. The best LLM is usually a fast, cheap model with a flagship escalation path — not the arena #1 for every turn.

Weight speed and cost on the leaderboard, check quality so the bot is not nonsense, and look at moderation flags. Then run your top 20 support macros in the arena.

Cheapest models in the live catalog

Live OpenRouter pricing and Arena quality, cached about an hour. Not a static blog table.

Model	Provider	Blend $ / 1M	Quality	Context
Mistral Nemo	Mistral	0.02	—	131,072
Ling 3.0 Flash	inclusionAI	0.04	—	262,144
Llama 3 8B Lunaris	Sao10k	0.04	—	8,192
MythoMax 13B	Gryphe	0.06	—	4,096
Nex-N2-Mini	Nex Agi	0.06	—	262,144

TTFT vs tokens per second

The first token must arrive quickly or the UI feels dead. Streaming hides total generation time but not TTFT. See the arena metrics and the tokens-per-second explainer. A slightly worse model that starts in 200ms often wins UX.

Grounding

Support bots should be RAG bots. Pair a cheap generator with your help center. The RAG guide matters more than chatbot personality.

Tone and refusals

Consumer companions and bank support need different refusal policies. Catalog moderation flags are a start. Test jailbreaks and “speak to a human” flows.

Multi-model routing

Classify intent with a tiny model; answer with a mid model; escalate billing disputes to a flagship or a human. Use compare pages to pick each tier’s $/1M.

Observability

Log model id, tokens, and thumbs. When a new catalog row is cheaper at similar quality index, A/B it. This site’s hourly catalog refresh is how you notice that row exists.

FAQ

Should my chatbot use GPT-4-class models?: Probably not for every turn. Use a cheap model by default and escalate.
What’s a good latency target?: Under ~500ms TTFT feels snappy for chat. Measure in your region; our arena numbers are a relative signal.
How do I keep the bot on-policy?: RAG + system prompt + moderation + evals. Model choice is one layer.
Open-weight chatbots?: Viable if you can host and still hit latency. Compare open rows on cost and quality first.

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Rank chatbot-oriented models