Need a recommendation for heating 640 square feet efficiantly

Howdy from Texas!



Winter is coming and I need a recommendation for a heater. My wife and I live in a 6 room 800 square foot home. We have a window ac/heater for our bedroom (110 square feet) so that is taken care of.



I am looking for a recommendation for heating the rest of the house as it has no central heating. I was just planning on grabbing a small space heater for the bathroom. The remaining part I need to heat is a living room (247 square feet), kitchen and dinning (207 square feet) and another adjoining "laundry" room. This is about 640 square feet total with a few corners to heat around.



Our winters aren't too bad down here (extreme lows are in the 20's). We don't want to be cold!



I am looking for recommendation for a portable, efficient and affordable (I am willing to make a worthy investment) option. Any brands or model recommendations would be greatly appreciated!



Thanks so much for your time!