Motor maintenance....motor maintenance...we don't need no stinking motor maintenance! "We" are all of us who've made the wise move from gasoline engine power to cordless electric lawn mowers. It's all about the gasoline engine and involves messy / smelly motor oil, gasoline, fuel stabilizers and air filters and cleaning and adjusting spark plugs. NONE of that has ANY place in the lives of cordless electric lawnmower owners /operators!
For the majority of homeowners, size and power options are every bit as good today for cordless electrics as for gas engine models, unlike ~ 6-10 years ago. Their electric motors require NO MAINTENANCE! And quiet? My Neuton 14" cordless electric is so quiet I need not worry about waking neighbors with early morning mowing.
One important detail to look for which not all models employ is an in-use removable battery pack. NONE of these batteries for cordless electric function like to be "short cycled" (run for less than complete discharge before being re-charged) Buy a spare battery with the mower so you can run it to full discharge and then swap battery packs. That is pretty much just like refilling the old mower's gas tank from the can of spare gas all gas powered mower owners are OBLIGATED to keep around.
One more thing to look for: Rechargeable batteries don't like to be "overcharged" ( being charged even after they are at full charge) and are robbed of energy storage capacity and lifespan by it just like with “short cycling”, so look for one with a battery charger that has either or both auto-shutoff at full charge and /or full charge indication. The latter is usually color change of an LED light on the charger. Most makers have figured this out and met the need with both features but I'm not sure all have.
If you choose a Neuton, as a bonus there's a trimmer edger attachment that works really well and is super easy to operate.