I wouldn't classify anything that you can buy at Sears, Home Depot, Lowe's or any "warehouse" store as a garden tractor, but as only a mower. Here's why: a garden tractor is built much heavier (you definitely won't be able to pick up a NH GT22A by hand) with a thicker frame, heavier duty mower deck, etc. A true garden tractor will last a lifetime, something that you buy at a warehouse store certainly does not have that reputation. Other reasons why I would go with a New Holland GT: Cruise control, hydraulic implement lift, power steering, mower deck options, dual range hydro, versatility with attachments.
Also, don't forget, if you go with your local dealer instead of a warehouse store, you can get your garden tractor serviced at the dealer!!!