Diesel isn't really an option.
Yamaha or Suzuki, neither has a dealer in Tofino where I am all summer. Suzy is in Bamfield & Port (Breakers, and I've had good experience with them), Yamaha in Port. In Vancouver where it winters there are both.
Right now I'm leaning towards Suzy, mostly because of the great experience I have with the Suzy I have on my other boat; DF 140 that has been flawless to close to 500 hours.
That being said, both my kickers are HT Yammis; an 8 and a 9.9 that have run better and better the more hours they have on them. Found both vibrated more when they were newer.
What concerns me a bit about the Suzy's is that they are "new" in their lineup.
The Yamaha's are a tad lighter.
Bad experiences with Merc keep me away from that brand for now, although I don't have any really recent experience with Mercs so may just be my historical bias...