Difficult to pick a brand just like that. I have owned lots of outboards since 70s, and sterndrives too. I can just say that all brands have hade their bad days in engineering dept. Maybe Yamaha never had a bad model, but correct me if wrong...
Sooo. Mercury? Have only had 2 strokes but our 75 elpto from 2002 was great. Simple, sturdy, hard working. Would buy one again. 70s 4.5 hp... not in my life.
Johnson/Evinrude? Had a great 6hp '83 and a lemon 4hp '75. Also a rotten 60 hp circa '79 with an underwater electric gear taped "water tight"... arrgh. A friend have a 90 hp V4 VRO that will run forever it seems. Heard some bad stuff about early hi pressure 2T but I don't know..
Honda 4 strokes. Silk smooth. Some have costly maintenance though.
Yamaha/Mariner: Have an old 30 hp 2T and it's awesome. Also a 6hp '81 that you can start almost by whispering to it... And everyone I know loves them, 2T and 4T.
Suzuki: Seems to be on par with yamaha. Larger 4T very popular over here.
Conclusion: You can only talk about specific models, not brands. Avoid new models that have not proven themselves, most lemon designs get a bad rap quickly. The sea is punishing.
Check into service, some (not all) new 4 strokes sometimes have heavy maintenance costs, offsetting some of the fuel savings. (hint: timing belts. And catastrophic belt failures are grim experiences)