I started with a small ceramic heater. Wasn't happy with those.
Went to a parabolic heat dish Amazon.com: Presto HeatDish - Parabolic Electric Heater: Home & Kitchen
and I loved it because it pulled less amps (1300 watts as opposed to 1500 watts, do the math, watts divided by volts) and was quite toasty! But it took up a lot of room and the "light" on it was bright, and sometimes kept me awake, even though it was in the front of the RV and I slept in back. I don't close the door to the bedroom because I have a cat and it needs to get up for food and litter box.
I finally settled on oil filled radiators. I got a large one for the front of the RV, and a small one (that only pulls about 4-5 amps) for the bathroom.
If the lows are 40-60, I use only the large radiator in the front. If it gets below 40 at night, I use both the large one in front and the small one in the bathroom.