I have Max subscription to both Claude Code and Codex. I use both fulltime throughout the day. I have them check each other's work, and route tasks they are best at to the right one.

The checking each other's work is so helpful.

New features, mockups, I use Claude Code. Deep fact-checking, I use Codex.

My harness matters at least as much as the model. I use the best harness and then invest a ton in it