If both heaters of same kW rating have a thermostat and were set to same temp there should be no noticeable difference in efficiency. Consider the oil-filled option will take a little longer to heat the space to the stat temp, and gradually release its accumulated heat energy for some time after it is turned off.
Make sure your timer plug is rated to take the power of the radiator. I had this problem with a more powerful 3kw heater.
You shouldn’t let small children anywhere near one of these (annoyed)
Voted hot. These are not very fast . But these are safest . No danger of catching fire like with other electrical heaters . Also very good around small children.
Also bought one last time, very happy with it, added timer plug to switch on at appropriate times.