I think aero is supposed to be the fastest, but I haven't seen a difference between
under current(rdwc) and aero. I have no experience with flood/drain so cannot speak
for that.
I don't think there is one system that will give you way more yield, as that's too much
based on genetics/experience/lighting/veg time.
So far I'm really digging my under current system. It delivers tons of air to the rootsystem,
simple to build and maintain, easy to clean, and the growth is tremendous. There's a whole
subforum devoted to this method over at thcfarmer if you wanna check it out.