I use the ST sensors, as geofence is too large for my needs (either have to offset it from my house, or when i'm at the pub or in-laws it thinks i'm home).
I currently have 6 of them in use;
1 has been adapted to run off AA's for the wife's car , it's still in it's housing which is then inside a 4aa holder, so can still run it off the button cell if i want. This has been sat in her car for at least 9 months and still shows 100%
1 on my keys,
1 on the wife's keys,
1 on each of the two kids bags
and lastly 1 for the dog walker
In 12 months i've only changed the button cells once in each of the keyfob versions and the ones that are in the house are currently showing 100%, 90%, 90% & 70% The dog walkers is showing 90% but that'll update tomorrow when he comes.
Back when i was on ST, i added a zigbee repeater as close to the front door as i could get it and that helped massively with the reliability. I've had no issues with them since switching everything to hubitat.