We just went through this for a new electric start short-shaft 15hp for my boat club. It came down to (listed alphabetically) ... Honda, Mercury, Suzuki, Tohatsu(Nissan) and Yamaha.
-The Yam was ruled out as being the heaviest and members with newer ones have TONS of problems with them. Two, only a few years old, both had to have new carbs put on them to get them to run. I have the OEM service manual and many years experience on OBs and I could never get them to run 'well', where 2 local Dealers also tried their hand to no avail. New carbs did the trick ... now, for how long????
-Honda was ruled out as they are heavy and our local Dealer won't deal on pricing, which left it as the most expen$ive we looked at. Plus the are notorious for only servicing - by priority - those who buy boats and motors and yard space from him. Just buy an OB and need service or God forbid any warranty work? Go to the end of the line and maybe he'll look at it in August when you dropped it off in May ...
-Mercury was ruled out as it turns out that Tohatsu makes all the smaller HP Mercury motors anyway! Plus Merc-induced changes for the tilt lever (and one other feature I forget ... ) isn't placed in a position as user friendly as the base Tohatsu model.
-Suzuki wasn't considered due to local Dealer availability.
Summary - We feel we got the best price and value going with the Tohatsu. The Dealer also let us buy it this past Fall (to save/guard against any future inflation price increases) and they'll have one ready for us by the end of March, where they will put break-in hours on it in their test tank prior to pickup.
All the other Dealers were - You buy it, you own it, you take it ... now ...