AC's do push more gph, Ac's are very good for mechanical filtration, while Emperors are moderate in chemical and mechanical, I would suggest getting Ac's for larger messy fish, and get a cannister filter to help even off chemical.
I have 2 emps. one on each 55 gal. I like them pretty well. Next Hob filter I get though, might be an AC 110. I hear alot good things about them. I want to see how good they are.
Sooooo, put bio-wheels on your AC's!
It's relatively easy and you end up with the best of the best, see my thread on modifying the AC110. Chile's Bio-Wheel Mod