All electric heaters are 100% efficient, save for any energy they use for fans/lights/making noises/bluetooth/wi-fi.
Define efficiency? To me, it is how much heating is required to heat and maintain the required temperature over a given length of time. How efficient each heater is, will vary as the length of time changes.
So the room has heat loss, this will increase the longer the room is heated, not linear but more logarithmic so hard to quantify the loss. But a room which takes 2 hours to heat will have more losses as one, which takes 15 minutes, to heat. So the faster it can heat the room, the better.
The fabric of the room and things in the room will absorb the heat, and will release it after the room is no longer being heated, also the walls are often colder than the room, so moving air to heat the walls can be counterproductive, with more energy leaving by the windows. So use of a fan is a double edge thing, it gets heat into the room faster but can also assist it leaving the room.
So the best heating for one room may be an oil filled radiator giving a constant output of heat, but the fan heater, or inferred, may be better for another room, and the time the room is required for matters.
I made a mistake fitting underfloor heating in a wet room, one, the shower cooled the floor in a few seconds, and two it could take 2 hours to reheat, totally wrong heating for the room.
We see this with heat pumps, they are so slow getting a room to temperature unless the room needs heat for a long time, rather useless.
However, not talked to anyone where geo-fencing has really worked. It simply takes too long to heat the room. Most rooms take an hour to warm up, so geo-fencing needs to trigger 30 miles away to work. With mine nearly home before it kicks in. And of course you would need to work 30 miles from home.
Define a lifestyle and room, and one can give some sort of answer, likely work well in a kitchen. But I tend to work on near enough engineering.
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