I agree to avoid salt water boats if possible but since you are looking at a newer model (5 years old or less), I’d be open to a salt water boat if the deal was right. Just anticipate having a few salt water related gremlins.
I’d also stay away from the blue engines, more maintenance requirements and increased likelihood of having drive problems.
Having owned our 370 for a year now, IMO, it will fill most people’s needs and we love it. I’d consider a 400 if, like mentioned above, you were going to cruise a lot in which diesels make sense but like also mentioned you are going to pay a premium. I’d also consider a 400 if you plan to have extended overnight trips. We overnight almost every weekend in our 370 but after a couple days it does feel a bit cramped. I believe the increased size of the galley, bigger cabin refrigerator, and the easier access to the aft cabin would make it more enjoyable when overnighting. When I was looking for our 370, there always seemed to be more 400’s to choose from, my assumption is there were a lot more 400’s built than the 370.