There is no oil, no fuel, no sharpening blades, no noise, or a lazy boy with blades on the wheels.
Fiskars maxreel reel mower, which was purchased in 2018 and has truthfully mowed a quarter acre lawn since then. While I have tightened them twice (each spring) to make sure they are cutting properly (use a piece of paper to measure cut-can show you how), the chain is frequently oiled and blades are self-shaven. Front or rear grass discharge and adjustable cutting height.