Fireplaces typically send a lot of heat and air up the chimney, and don't put much heat in the room or house.
They also heat one room, but not the rest of the house.
So, they tend to be a poor way to heat, be they wood or gas.
I'm probably biased because I live in Minnesota where it gets really cold for really long periods of time.....
It doesn't work well to put a fireplace in one room here and upset the distribution of heat throughout the house from the main furnace. And it is just folly to try to heat a whole house with one fireplace here....
In more moderate climates it probably works better?
Gas is cheap.
Wood can be cheaper, but more work.
Electric is expensive.
If I need a few degrees of heat from time to time I would use an electric heater that costs $60.
If I need to heat a portion of the house for real I would go with a wood or gas heater. I would not like a ventless unit in a house.
I find the electric 'fireplaces' to be overly expensive for what they are, and expensive to run, and look fake and silly after all that, so I just wouldn't bother with an electric fireplace at all.
Um, what was the question again?
Paul