Your best bet is to skip the Home Depot and Lowes mowers and go to a tractor dealership.
www.deere.com has all the info on buying something that will perform and last allot longer than the cheap knock off's from HD or Lowes.
That being said, You can pick up a John Deere Zero 717 new for close to the same cost of a residential model, and it will perform much better. Also try Hustler, Toro, Gravely, and Scag.