All electric heaters may be close to 100% on efficiency, but how they heat can make a big difference on how comfortable they make you feel how fast.
We have just recently learned the difference. We have two electric heaters we can use in our RV but have decided the one is definitely more comfortable than the other, even though both are 1500 watt electric heaters.
One heater blows hot air out the front of it (heats only the air in the RV). The other heats radiantly (heats objects in the RV that slowly heat the air).
Our radiant heater is vastly superior in our opinion - same electric bill as the air-only heater. Our bodies immediately feel warm when we turn the radiant heater ON - warm air eventually results - but our warmed bodies satisfy immediately.
Of course the propane furnace is an air-only heater, but it's BTU rating is so high that it forces the comfort to come fast because it heats so much air so quickly.