If you're fed up with Windows and like OSX, Parallels provides the best of two worlds. You can run Windows apps at near native speed, and if using Coherence, you even share the same desktop. When running other stuff, you don't have to put up with that ancient MS stuff anylonger.
Can't say much about WinUAE performance since I'm not a regular user of that program, however the virtual x86 runs at near native speed since it uses modern virtualization technology.
-- Peter