claude, gpt, deepseek or openrouter: which model to choose for your agent.
heysteff is an AI platform for customer support and sales across WhatsApp, Instagram, Messenger, Gmail and Shopify; Steff is the AI agent that runs it. Behind every one of Steff's replies there's a language model (LLM) doing the work of understanding and interpreting the message — and not all models are equal, nor does the same one suit every business.
◆ key idea
There is no "best model" in the abstract — there's the right model for your use case, your conversation volume and your budget.
What actually changes between one AI model and another
When someone asks "which AI model is best?", they're really mixing several different questions. The language models available today — from providers like Anthropic, OpenAI or DeepSeek — differ along at least four axes that genuinely matter for a customer service agent: reasoning quality, cost per conversation, handling of Latin American Spanish, and the ability to read images (vision). No model wins on all four axes at once; every provider optimizes differently.
Reasoning quality: how well it follows complex instructions
A customer service agent doesn't just answer simple questions: it has to follow your business rules (what it can promise, when it must escalate), hold context across a long conversation and decide when to use a tool — look up an order, book an appointment — instead of just chatting. Each provider's most advanced models handle that complexity better, especially in long conversations or with specific business instructions. For a simple use case (answering hours, location, FAQs), a lighter model is usually indistinguishable in quality and quite a bit cheaper.
Cost: why the most expensive model isn't always the best choice
Cost per conversation varies a lot between models, and not always in direct proportion to quality. A business handling thousands of simple conversations a month (hours, availability, order tracking) can get practically identical results with a more economical model than with the market's most expensive one, and save significantly in the process. The relevant cost isn't "how much the model costs" in the abstract, but how much it costs to resolve your real conversation volume well.
Language: how it handles Latin American Spanish
Not all models understand regional nuances of Spanish equally — idioms, local slang, the difference between asking for something formally or informally depending on the country. For a business serving customers across several LATAM countries with different idioms, it's worth testing how the agent actually sounds in practice, not just trusting a model's generic spec sheet.
Vision: not every model reads images
If your business needs the agent to read photos of products, payment receipts or labels — increasingly common in ecommerce over WhatsApp and Instagram — that model has to be multimodal: capable of processing images as well as text. Not all available models are, and among those that are, the quality of reading text inside an image (an amount on a receipt, for example) also varies. We go deeper on this in our article on computer vision in customer support.
heysteff's approach: model configurable per workspace
Instead of betting on a single provider and forcing every customer to use it, heysteff lets you choose the AI model per workspace among Anthropic, OpenAI, DeepSeek or OpenRouter. OpenRouter in particular is a gateway to hundreds of models from different providers with a single integration — useful for businesses that want to test and compare without depending on one brand.
The choice can even vary by task type within the same workspace: one model to chat with the customer, another for internal tasks the end customer never sees. There's no dogmatic stance of "provider X is always better" — the recommendation depends on your volume, your budget and how critical reasoning is in your typical conversations. If you're not sure where to start, in a demo we'll review your specific case and test with real data from your business.
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◆ next step
Test different models with your business's real conversations before deciding.