Another vote for 120, but the lower setting should work just fine, too. The standard rating for equipment is 115 volts +/- 10%, although the labels for Made in China stuff can be all over the place. Do you use more AH's on 120? IMO that's hard to say. Loads like incandescent lights, hair dryers, and microwave ovens will use more. But the lights will be brighter and the hair dryer and microwave will do its job faster. The inverter efficiency might be better with the high setting, or at the low setting, or it might be the same at either. I think you'll have to do a lot of measuring to get the answer.