They are the best designed desktop-level machines out there,in general.
I am happily building the whole Mudcat CD project on a dual processor G4 running OSX 10.1, and it is doing everything I could possibly need.
They get better performance per hertz in terms of megaflops or other objective massive processing tests than there Wintel counterparts.
It is also true that since they emerged from the Swamp of NT, withthe advent of Windows 2000, Wintel packages have been a lot more stable., But they still require a lot more attention to the tool which proportionately eats up attention that could be spent on doing the job.
Depends on your taste, of course. There is no shortage of software for Macs, even under OSX. Using both systems every day, all I can say is my horizons brighten when I get home to my Mac because it seems much "friendlier".