The tools all do roughly the same thing: you type what you want in plain English, they write back. You don't need to learn a new language or any special syntax. If you can describe the task to a sharp new hire, you can do it here.
There are four general-purpose ones worth knowing. Pick one and get comfortable — they're more alike than different. Each has a free tier, plus a paid plan (around $20/month) that unlocks the smartest models and the image tools — and gives you a lot more usage time.
One more, for a different job — Perplexity. It isn't a fifth general-purpose chatbot — it actually runs the other models under the hood — but it's built for one thing in particular: searching the live web. When your question has a real-time answer — current prices, recent news, "who makes this part and what does it cost right now" — Perplexity searches faster and more thoroughly than the others do off the bat, and shows you its sources. Reach for it when you're using AI as a research tool; reach for the four above for writing, reasoning, and ongoing project work.
The one-line takeaway: the free versions are enough to learn on. Once a tool starts saving you real time every week, the ~$20/month paid plan pays for itself almost immediately.
Picking a model — and what it costs you
Inside a tool you'll often get to choose which model answers — a fast everyday one and a more powerful one. (On Claude it's Sonnet for everyday work and Opus for heavy lifting; ChatGPT and Gemini have the same idea under different names.) The more powerful model can reason harder and hold more in its head at once — but it costs more to run and burns through your usage allowance faster.
The rule of thumb: let the standard model handle the everyday work, and only switch up to the powerful one when the task genuinely calls for deep thinking — dense analysis, a long and complicated document, anything where it needs to hold a lot together and reason carefully. For quick drafts, rewrites, and summaries, the standard model is plenty — and staying on it keeps you from burning through your usage limit halfway through the day.
You're a Microsoft shop, so Copilot is already sitting inside Word, Outlook, and Excel — and that's exactly where it earns its keep: for work on your own files and documents, where it already has the context, use it right there. For more general, everyday AI work it tends to feel clunkier than the big three, so for that I'd step outside it to ChatGPT, Claude, or Gemini. Right tool for the job.