Any HVAC guys here, I have question

Electricity = 3413 BTU per KWH
100% efficient

3413 BTU per 0.114 dollar
Therefore electric gives 29938 BTU Per dollar

A propane water heater will have slightly worse
heat loss (than electric) when not running, due to to the flue running up through the tank. This isn't a huge effect, maybe another 5%. Propane would allow a smaller tank size, due to its faster recovery rate, so the smaller tank could compensate somewhat for the flue loss.

Bottom line is the cost of water heat is about the same either way, with perhaps a slight advantage to electric.

In my opinion it does not yet make economic sense to buy an electric water heater to "save money". Your payoff for the capital investment would be very long at the nearly insignificant difference in operating costs.

I know of many tankless installations, and the gains if any were minimal. The one big advantage to a tankless - is in a house with several places that need hot water that are far from the one cental tank heater. In that situation, there's a lot of heat loss through long runs of pipe. In that sort of case, several small tankless heaters at each location can make a difference.

Electricty gives around 3400 BTUs of energy per 1 KWh. That comes to .00003 of a cent per BTU.

Propane gives around 91,500 BTUs per gallon.
That comes to .000027 of a cent per BTU - but the propane has some heat loss out the vent pipe.