Having just been through a rather painful experience with the installation of a new outboard I would say what is far more important than the make of engine is from who are you going to buy it, rig it and then maintain it with.
All the big manufacturers, Mercury, Evinrude, Suzuki, Yamaha, Honda produce good engines however there are loads of dealers out there that could not rig a set of Christmas tree lights.
So I would look at who you have locally to you because if anything does go wrong you dont want to have to drive 2-3 hours to get there (and back) and then speak to people that already deal with your chosen local supplier to make sure he has a good reputation.
I have just gone this and it almost put me off what is a perfectly good make and type of engine. Now I have redone most of what they did myself and I am very happy.