Re: Johnson Outboards ???
Choosing one brand over another depends on what models you are considering and the availability of service/parts in your area. For example, the 60* V6 carb Johnnys and 60* V6 carb Mercs, are nearly the same displacement and design. Both are fine motors. if you are looking at these, pick the one with the best service+parts availability.
As for other models, usually 3 cylinder 2 cycle motors are better than 2 or 4 cylinder 2 cycle motors, of the same HP. They are lighter than the 4 cylinder models and run smoother than either 2 or 4 cylinder motors. Comparing 2 cylinder motors of different brands, is likely a wash as well.
If you are comparing Optimax with e-TEC, I think it is a toss up. I personnelly like the Optimax design better since you are compressing air vs fuel, but both are fine motors.