I suppose it truly boils down to personal taste? My take[0] on AI including harnesses.
[0]: https://a.l3x.in/ai
If you drew a venn diagram of their prospective users, the overlap ain't gonna be big. I get that they're both harnesses, but claude is clearly trying to optimize for the agentic development loop, while piagent is more about hand holding - unless you add the agentic features yourself (which is pretty easy, but again completely different target audience to cc).
I bounce between codex and cc all the time. There is no moat there.
They all have some annoying downsides and I use CC the most, but it's gotten to the point where I'm for sure actively shopping around for better harnesses.
I use the models but not the "harness" though. Not directly anyway. I am still handicapped by the CLI when running in Paseo. Both antigravity and agy are toys compared to what has been available for at least two years.