I'm looking at purchasing a boat primarily for fishing on the Chesapeake Bay. I'm not sure about a lot of things, so I've been checking out boats I like and researching them. Got a couple questions though.

Boston Whalers and Grady White's seem to be pretty darn good boats right? I'm interested in something from 24-27' that I can pull behind my truck. Just curious, but how come some boats have I/Os and others have 2 or 4 stroke outboards? What are the advantages/disadvantages of each? Most of the GWs and BWs are single or dual outboards.