What do you want your boat to do:
A) Go FAST!!! (Dual outboards, 2 or 4 stroke)
B) Get decent fuel economy (Inboard V-8 with counter-rotating prop sterndrive)
C) Be (fairly) inexpensive to repair-engine anyway (See B)
D) Be able to work on it yourself-engine anyway (See B)
Etc.
Etc.
Spoke with a fellow who had just trailered his 32' Bayliner Command Bridge out of the Everett launch. He had a built 454 gas engine with a dual, counter-rotating prop sterndrive. He couldn't say enough about it's power and handling.
Personally, If I could get it, I would have twin diesels/sterndrives on that size boat.
Went out with a friend who owns a 25' Bayliner Trophy with twin 175 HP Merc 2 stroke outboards.
Advantages:
Plenty of power out of the hole, tight turn radius and, a 55+ knot top speed.
Disadvantage:
High fuel burn (Don't know how much per hour at full throttle, but quite a bit)
What I have heard (and correct me if I'm wrong) is if you take the horsepower of a 2 stroke outboard and divide the number by 10, you get approximately the gallons of fuel burned per hour at full throttle or just under.
(Example: I have an 85 HP Johnson outboard on an 18' tri-hull. In calm water, at full throttle, I burn approximately 8.5 gallons per hour).