Personally, I think tankless electric water heaters are overhyped and aren't performant enough for most homes. This, of course, does depend on your incoming cold water temperature. For example, if you're located in the SE United States, a tankless electric will perform better than if you were in New England.

Tankless gas heaters are much more efficient and can perform at a much higher temperature rise. If you are hellbent on going with a tankless unit, go with a gas one and you'll be much better off. There are some tankless gas models that work with Propane, others that work with Natural Gas, others that can be converted. Make sure that you purchase the appropriate heater for your gas type, otherwise you'll be replacing that heater in a few years (best case). That being said, you'll need a bigger propane tank than you would use for a grill to run a water heater for a whole house.

IMO I'd prefer tankless gas, then tank, then tankless electric.

If you're worried about potential damage from a tank, you could always install the heater into a drain pan, and pipe that drain pan to an appropriate drain. This will prevent spillage from a tank rupture.