I also went through this about 2 years ago and decided on a 30hp honda with power tilt/trim and electric start.

A couple things to look at and think about are: what is the max hp of the boat, what shaft length you need, what features do you want in the motor (power trim/tilt, electric or pull start, etc) and how much you want to spend.

After you have figured out what you want, start comparing engine prices, features, weight and tiller handles. I looked at Honda, Yamaha, Suzuki, Mercury, Johnson, etc and found that the honda 25/30 were the same weight at 187lbs, had a great tiller handle and both came with power trim/tilt and electric start, Yamaha only made a 25 high thrust model, was over 200lbs and didn't have ptt and electric start, Suzuki's 25/30 were over 200lbs, only the 30 had ptt and elec start and the tiller handle was pretty weak looking, mercury had a 30/40 engine that was about 250lbs, its tiller handle was very weak looking and had heard that was terrible at cold weather starts but now has EFI in their engines so they might be better.

One last note. If you plan on fishing higher elevation lakes in the sierra's, buy a second lower pitched prop. Because I fish lakes from 0 to 8000', I have found that I needed 3 props. One for 0-3000', one for 3000-6000' and one for heavy loads or lakes above 6000'. Elevation takes away about 3% of your power per 1000' feet.