I agree with Frank, Sandy. For the amount of money you are spending on lawn mowers, you'd be better of dollarwise hiring some kid to come in and mow your lawn!!
Personally, I have a Craftsman Riding Mower with a Briggs/Stratton engine. They're the best. Plus with Sears, you get warranty and service calls that you can't really beat.
I don't know how much lawn you are mowing ---
mulching is good, self-propelled is good, keeping the blades sharp is a must!!! Maintenance on the engine is also a must...even just keeping it clean.