As far as g1s go, I really like all of the twinkle-eyed ponies and the brush-n-grow series! I only have one from each, though...Although it's unlikely, I'm always on the lookout for them at thrift stores. I found my masquerade that way!
With G4s (which I have many more of), I've been slightly obsessive about collecting the newest pearly-bodied series. Unfortunately, it seems that wave 3 was completely skipped in the united states and those are the last four I need to complete it. Womp womp. :\