Which AI coding tool should I use?

Short answer

For agentic work in an existing codebase, terminal-based tools like Claude Code and OpenAI's Codex are the current default. For editing with AI assistance in a familiar interface, Cursor and GitHub Copilot suit people who already write code. Gemini is strong on very large contexts. The honest answer is that the differences between the frontier tools matter far less than how precisely you can describe what you want.