My boat has a Honda for going on ten plus years now with very little problem. I'm on the Chesapeake so you could debate whether that's salt or fresh, but it's never been flushed. I'm sure I've just jinxed myself.
In everything I've read, the Yamahas get high praise as well. The decision point for me would be which had the best local support. My local Honda dealer closed their doors a while ago and now I've got no one to go to for repairs that I'm either unable or unwilling to do. Same for parts. Even when I can do a repair or maintenence myself, I can't get the parts locally so I have to get them by mail whuich elongates my repair time.