I really like the tunze nano stream powerheads. Small and powerful. If you need more flow then you can modify them. What kind of corals will be in the tank?
Koralias are too big in my opinion. But two koralia 2's would do good in a 24x24x16. Koralia 3 is too strong.
you'll use waaaay less energy if you go with in-tank circulation pumps like the koralias. If SPS frags, a couple k2s would be great IMO. If softies, you could get by with less...