I don't understand how people can like Clazziquai over Portable 1 and 2 if for no other reason than Clazziquai has a really crappy framerate. The first two games feel smooth as butter by comparison.
Portable 3 looks nice and doesn't really have the framerate problems of Clazziquai, but the mechanics feel weird. You can't just willy-nilly play notes when pressing the buttons, and the individual sounds sort of cut out permanently when you miss long notes... I dunno, I feel like I have less control when playing. Also, the song selection is poor.
I haven't tried Black Square, mostly because it has that auto-correct "feature" which I want to avoid...
Hot Tunes is a good compilation of the first two Portable games and doesn't have the auto-correct crap that Fever and BS has... but I am not really liking some of the challenges (though I'll admit I'm far from the best player in the world, lol).