I'm with BullMerc - of the three option you listed PHX is, by far, the best overall. Ride, storage layout, performance in all kinds of conditions are superior in the PHX. That said . . .
Fuel efficiency will be more a function of how you drive your boat than it will be a matter of which boat you chose. In my Triton, the 5200-5400 rpm range is kinda the sweet spot. My buddy's PHX is a little higher - around 5500-5600 rpm. If you load it up w/ tackle and people your fuel efficiency will suffer. If you keep it loader lighter it'll improve. Yes, some hulls are inherently more efficient by design but I don't know that it's discernible. Driving in the sweet spot range compared to running WOT all the time is very easily discernible.