>>trouble free
Currently, the brands are all lightweight, plastic-y, and under-powered. The blades consist of 3 or 4 razor-like blades mounted on a disk. The only reason they can mow is that they only have to lightly trim the grass ...but that means mowing must be done several times a week, adding to wear & tear. On some, the switches and control panels are exposed to the elements. Overall, I'd guess that their life expectancy is 3-4 years even with good care & maintenance.
The other problems come from the yard itself. Branches, pine cones, flower beds, stray garden tools, toys, equipment, slopes, sandy spots. Over the past decade, they've gotten better at handling yard problems but they still get stuck or suffer from temporary dementia and you have to go fix it.
And then there's theft.
For me, an ugly, brutish, open-source kit will probably be the answer. (Damn the safety features! Full speed ahead!)