Ryobi and Troy 2 or 4 strke should not be discussed. Not worth your time.
Now, in terms of four stroke, Honda make a nice rig, but it's heavy. The one no one has mentioned that you need to check out is the Dolmar. They weigh the same as equivalent performing 2 strokes, and are great machines. No compression to fight, one pull start, low fuel use, quiet, no stink and torque out the yahoo. And the prices are great. Go look them up.