A year and a half ago I went through this process and decided on a Honda 20HP 4 stroke. Not many of the manufactures make a 20HP and the Honda is in the same case as the 15HP and not much more weight. I think on Mercury you have to step from 15 to 25 and the size and weight were too much for my boat. I've had no maintenance problems and it's easy to perform the oil change at home. It's a little more expensive but is pretty comparable to the Mercury and Yamaha. I got one with the electric start and electric trim and tilt to that jacked the price up quite a bit.