I have owned over 12 boats over the past 35+ years.
Here are my thoughts (YMMV) -
I will NOT buy anything these days that is not a 4-stroke.
Although the Etec is a very good motor - still, it's 4-stroke for me.
Honda is great, but they cost the most.
Yamaha is a VERY close 2nd to Honda.
Merc comes up next and is what I currently have on my new Lund Rebel XL 1650.
(Almost regret I didn't pony up with the cash and go with the Honda - but my new kicker I am having installed this week is a Honda)
Merc is louder that a Honda or Yamaha for sure.
But Mercs are also lighter, and less money.
My personal preference is Yamaha 4-strokes.
I know a LOT of people with them and they never have problems.
And they are very quiet.
My buddy starts his at the dock, does a few things, and then forgets it's running because you can't hear it and goes and hits the key again all the time.
They are quiet!!
There is a reason that you see them all over the place up north at remote Canadian Fishing Lodges and Resorts.
Good luck.