I would definately say go with Japanese. Honda, Yamaha, Suzuki and Nissan ( had a 50hp and it was GREAT ) or Tahatsu (Tahatsu makes Nissan ). Look at the dealers in your area as well. Its important to have someone close to work on it when and if something goes wrong. I would not say to over look Mercury either. They have gotten alot better plus you can always find someone to work on it.
In my area its all OMC and Mercury dealers. I have a Honda ( LOVE IT by the way ) but I have to drive an hour to the closest dealer for service and repair. Not exactly convenient but its not that bad. Just something to think about.