I have 3 Stihl saws and 1 Stihl weedeater. So I'm partial to Stihls. Wish I could give more experience with many trimmers, but this thing won't die.
I'm at work so I can't remember the model right off 'cause I have had the thing for almost 18 years.
Straight shaft(a must!), handlebar grips with shoulder strap(easy on the back), and it has had 2 spark plugs put in it since I bought it new for around $300 I think. Never had another thing done to it, except I bought one of those heads with the 3 nylon blades that chew up everything in sight.
I trim a large country yard and have shown it no mercy on the dam of our pond and in the woods.
I never do anything to the fuel between seasons and it always fires up. Now that I bragged, it will probably blow up..........
edit: looks like this, but not sure the model of mine exactly..........these are in the professional category on this site>>> http://www.stihlusa.com/trimmers/FS250.html