Which AI model for which task? A practical cheat sheet
Rules of thumb from shipping all four models in one app: GPT-5 for structured writing, coding, and careful reasoning. Gemini for long documents and research synthesis. Grok 4 for news, voice, humor, and image/video generation. DeepSeek for high-volume, repetitive work where efficiency matters. When in doubt, start with GPT-5 and switch when it feels slow, stiff, or stale.
"Which AI is best?" is the wrong question — like asking which kitchen knife is best. We ship GPT-5, Gemini, Grok 4, and DeepSeek side by side in GO AI Chat and watch the same prompts hit all four daily. Here's the mapping we actually use, qualitative on purpose (benchmarks age in weeks; task judgment holds for quarters). As of August 2026.
The cheat sheet
| Task | First pick | Backup | Note |
|---|---|---|---|
| Reports, docs, structured writing | GPT-5 | Gemini | Holds format & constraints to the end |
| Punchy copy, hooks, social posts | Grok 4 | GPT-5 | Native energy; edit down, not up |
| Editing your existing draft | GPT-5 | Gemini | Restrained; keeps your voice |
| Summarizing long material | Gemini | GPT-5 | Strongest with lots of source text |
| Coding — first attempt | GPT-5 | DeepSeek | Most often runnable as-is |
| Code review / second opinion | Grok 4 | DeepSeek | Disagreement is the value |
| Math with shown steps | GPT-5 | DeepSeek | Always ask for steps |
| News & current events | Grok 4 | Gemini | Freshest instincts; verify links |
| Research synthesis | Gemini | GPT-5 | Then verify citations yourself |
| Translation drafts | Gemini | GPT-5 | Native review for anything public |
| Brainstorming odd angles | Grok 4 | DeepSeek | Ask for 20 ideas, keep 3 |
| Voice conversation | Grok 4 | — | True two-way streaming voice |
| Image generation | Grok / Imagen 4 / OpenAI | — | Three families, pick per style |
| Video generation (≤15s) | Grok | — | See our iPhone guide |
| Bulk/repetitive prompts | DeepSeek | Gemini | Efficiency is the feature |
The one-line personalities
- GPT-5 — the senior colleague: reliable, structured, occasionally over-cautious. Default starting point.
- Gemini — the researcher: happiest when you hand it a pile of material and ask for sense.
- Grok 4 — the fast friend who's always online: current, funny, multimodal; verify its bolder claims.
- DeepSeek — the efficient workhorse: unglamorous, surprisingly capable, great value at volume.
Three workflows that beat any single model
Draft → restructure: Grok 4 for the energetic first draft, switch to GPT-5 in the same thread: "keep the voice, fix the structure." Research → write: Gemini to digest sources, GPT-5 to write the deliverable. Build → review: GPT-5 writes the code, Grok 4 attacks it. Every one of these relies on mid-conversation switching with context intact — which is the entire reason we built GO AI Chat as a multi-model app rather than another single-model wrapper.
What no model is good at (August 2026)
Citations you didn't verify, arithmetic hidden in prose, niche API surface details, and anything where being confidently wrong is expensive. Model choice mitigates none of these — checking does. For a deeper head-to-head on the two most-asked-about models, see Grok 4 vs GPT-5.
FAQ
What is the best AI model overall in 2026?
There isn't one — GPT-5, Gemini, Grok 4, and DeepSeek each lead on different tasks. The practical skill is matching the model to the job, or using an app that lets you switch mid-conversation.
Which AI model is best for writing?
GPT-5 for structured, constraint-heavy writing; Grok 4 for energy and edge; Gemini when the writing is grounded in long source material.
Which AI model is cheapest for heavy use?
DeepSeek's efficiency is its calling card, so bulk workloads route there. In GO AI Chat all four share one subscription, so per-model cost stops being your problem.
Do I need different apps for different models?
No — GO AI Chat includes GPT-5, Gemini, Grok 4, and DeepSeek with mid-conversation switching on iPhone, iPad, and Mac.