I found the Copilot harness generally more buggy/disfunctional. After seeing a "long" agent response get dropped (still counts against usage of course) too many times I gave up on the product.

It doesn't matter how competent the actual model is, or how long it's able to operate independently, if the harness can't handle it and drops responses. Made me think are they even using their own harness?

At least Anthropic is obviously dogfooding on Claude Code which keeps it mostly functional.