Yanmars are good. If your gonna have inboard engines in a big boat, they better be diesels. My buddy in Cypramore point runs a 31ft Contender with twin 225 Yamaha's. Great boat for nighttime spec fishing. He also has a 23 ft Grady white with a single 225. Just as good a boat. My other buddy out there runs a 31 ft Grady White with twin 225 yamaha's. Can you get the boat you like with a bracket for outboards? Man those things have come a long way, and are very efficient for moving big boats.
We need some more info here. What uses do you intend mostly? What size boat u looking at? I'd stay away from gas inboards.