A lot of the 433/915 band devices you can pick up with rtl_433 seem to be much more bullet proof and have longer battery life than equivalent WiFi and Zigbee devices too. Building new protocol decoders for rtl_433 also surprisingly isn't too bad either. One of my favorite ones is the water meter decoder which has saved me a lot of money when I've had irrigation water leaks and not noticed them (but saw conspicuous usage patterns reported).

ive got ~15 deployed sensors/transmitters and I haven't touched a single one in 14 months since initial setup. its super reliable if you can get your receiver/antenna somewhere that works well.

WAY cheaper than the other options too.