RenderDoc is very cool, but more of a high level debugger, I guess? It's also good to analyze performance issues, e.g. when working with QML and QSG_VISUALIZE=overdraw / batches (both very high level) don't cut it anymore, or to get a different perspective. Watching a scene getting drawn API call by API call is fun.

RenderDoc is mostly a frame debugger, although it does support stepping through shaders as well which can be super useful. But for real performance analysis I would use PIX if you target D3D12 or RGP and Nsight for Vulkan. I'm at a Vulkan and Metal only shop and I wish I could use PIX for my every day work, since it also has excellent support for Intel GPUs.

nsys and nvtx are awesome.

many don't know but you can use them without GPUs :)

That's true. It's pretty good for all kinds profiling. I especially like the python GIL profiler of nsys.