Just to be clear, if you can find an older Briggs and Stratton, I would agree with the above. Older models are a tough motor. There is one in my Troy Built lawn tractor that is still working seamlessly after 9 years of cutting an acre and a third. I'm not sure what year it was taken over by a new company but if you compare an older B&S engine with something you'll find in a store today, you easily will see that they have gone the route of lower end, mass market production.
Also, I second that a lawn tractor is not a high maintenance investment at all unless you buy an old beater. On the tractor mentioned above, I change the oil filter and spark plug every year, clean the air filter with some gas, sharpen the blades every couple of years and that's pretty much it. In nine years, I bought 1 new belt (it's hydrostatic) and had it tuned up twice. I repaired one flat tire by adding a 6 dollar tube. That's it for maintenance. Worry free yard racing.
However, if you can comfortably cut your lawn with a push mower, then I would still say don't bother with a ride on. Good exercise, you often need one anyways to get into tighter areas and the smaller engine produces less emissions.
