[hrothgars]

C.H.U.G. probably provides the most character variety currently, especially when you consider third party figures that have been produced in this scale.

Animated has quite a variety, but there are unlikely to be any new Animated figures created in the future. TF Prime is also currently limited as the series is still young. I love Masterpiece, but there simply aren't very many available characters.

Alternity is probably among the most limited as far as available characters. Binaltech & Alternators are cool and provide accurate 1:24 scale alt modes, but these too have a limited number of available characters.

I think signs point toward CHUG if you intend to ever develop a completionist's mentality or try to develop a wide roster of characters.

If you are comfortable in the Animated universe, you should still have a good time.