I have the same size lawn and am the same age as you. Never really needed a rider but have had several that were either gifted to me or bought for chump change. These include 2 John Deeres, a Troybilt, a Craftsman, and 2 rear engine 28 inch Snappers. One thing I have learned along the way is that riding mowers require a lot more maintenance than any walk behind. They simply have more moving parts and anything that moves will eventually wear out. Belts break, pulleys wear out or their bearings fail. Spindles fail. Decks rot out. Transmissions fail or in the case of the Snappers need to be adjusted. Springs break or fall off. Cables stretch or break. Seats get torn. Safety switches fail. Tires dry rot or just wear out. So, whatever you get be prepared to get your hands dirty or pay someone to fix the machine. You don’t need a big deck for your medium size lawn so I would advise sticking with a single cylinder engine. They use less gas and are simpler than 2 cylinder engines. Smaller decks fit through gates better and take less storage space, so don’t buy bigger than you need. Hands down the most robust of the bunch I have owned are the Snappers. Unfortunately, they stopped making rear engine Snappers so if you want one, you’ll need to find a used one. These mowers are the Model T’s of mowers. Nothing fancy but they are rugged and do a good job mowing and bagging grass/leaves, and they shift gears on the fly. Any of the Briggs flatheads are good but in my experience the 8 HP model has all the power you need. So, my advice is to find a used Snapper and either renovate it yourself or get one with a healthy engine, seat, and deck that has had all the wear components recently renewed, ie: good tires, newish clutch disc, good spindle and belt. Hope you have lots of years ahead, but chances are you’ll be done mowing before the Snapper is.