How much are you looking to spend?
Mongoose is not worth considering, they haven't been in years. SE is meh. Sunday is pretty good but I think they have silly colours, but that's up to you. You could check out Fit, wtp has some nice **** coming out this year, subrosa makes some cool stuff and so does pretty much everyone else. Redline, GT, Specialized, Haro, and Mongoose are all considered fairly worthless now, so stay away from those even if those are the classic names.
Looking at some bmx videos, what kinda tricks do you wanna do? Do you wanna go fast and big someday? Maybe a long-ish frame might be good for ya. Do you wanna do tailwhips and spins? Maybe a shorter frame or at least a short rear triangle.
Do you want a really sick bike? You say you're coming from ss/fg, are you into the whole custom thing? You could easily have a really pimp bmx for a fairly cheap price compared to a similarly blinged out fixie. If you're into that stuff go look at the bike check thread. That should give you plenty of ideas. Otherwise just about any complete will do you well.