Under a quarter acre, you're paying for simplicity, not horsepower.
For a small lawn the question is mostly setup hassle and price. Wire-free units win on convenience; a magnetic-strip or app-mapped boundary beats burying wire for a yard you could mow by hand in twenty minutes — the point is never doing it again.
Lowest upfront cost of any wire-free unit. A magnetic boundary strip replaces buried wire and vision helps it cope with some shade — strong for tiny lots and fast payback.
The coverage-per-dollar value leader for a standard suburban lot. You do bury a perimeter wire, but it's the cheapest way to mow a half acre on autopilot.
The cheapest credible wire-free mower. RTK satellite positioning, no boundary wire to bury — best for small, open, fairly flat lots.
Step-up i-series Navimow with better mapping. Wire-free RTK for small-to-medium open yards; wants clear sky for the GPS fix.
The wire-free pick for shaded lots: Husqvarna's EPOS satellite system is built to hold position under tree cover and overcast skies where plain GPS drifts.