As a small engine mechanic here is my view,
Push mowers:
Honda is best
A Briggs with a decently built deck will hold up pretty well too
Riders:
Personally i hate anything that isen't hydrostatic drive, but a belt driven tractor on a smaller lawn will do just fine. again Honda motors are the best but a briggs and kawasaki will last a long time too if you just keep on maintenance
Zero turns:
Stay away from any zero turns that are MTD as they put shitty pumps/drivegears in there machines and if you happen to get one with the ezt500 pump your looking at dropping 2k+ on a machine that will last 300 hours. As far as zero turns go, Exmark is the best.
I have no problem with my lower end mowers though because although i do have to do some work to them every year they always start and have had no major issues. I do wish i had a nice zero-turn everytime i get on that dumb uncomfortable 46" mtd and have to mow for 6-8 hours a week