Squirrel, you might want to have a look at this thread I started a year ago...
as I was asking the same question back then.
Ultimately, I bought Yamaha because of the availability of a really good deal (a demo engine from the Hurricane dealer).
I've only put a few hours on the Yamaha since I got it late last season. My initial reaction is that it's quiet, clean, fast, a little heavier than my old 2-stroke, gets great mileage and a is little sluggish out of the hole. (...provoking the E-tec dealer who winterized the engine to comment "I told you so"). I think I have the wrong prop on it though. I am changing props this weekend and I suspect that that will fix that issue.
Part of my decision was based on the comments made to me by the Hurricane dealer (long before his demo engine was available...). He sells every brand of engine as an OEM dealer, and according to his customers wishes. He commented that the Yamahas had proven to be bulletproof, that the Hondas were as well, but overpriced and heavy and that the Etecs were very high performance, but his customers had been having problems with the oiling systems. (He had sold six 150s to a tour company recently and they were considering changing them... BUT, they were using them in the Arctic where sub-freezing use was common.)
Personally, I was overwhelmed by the propaganda provided by the manufacturers. All of the head-to-head comparisons were contrived and meaningless in the real world I felt.
At the end of the day, I wanted a good, reliable, fuel-efficient engine at the best deal I could get... and I was successful I think. Had this deal not been available, and the prices had been comparable??? Hmm, likely I would have gone with the next important factor: LOOKS! My boat is grey on grey, and looks great with the grey Yamaha. It would have looked funny with a white or blue Etec!