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.
