Make sure you get one that will heat at low temperatures, Ours will heat down to -10 degrees, however we have LP backup so it is set to switch to LP at 10 degrees, roughly where the cost is the same.
With electric back up you may want that switch point at a lower temp.
IF your HVAC guy (or anyone else) tells you a heap pump does not work at low temps. FIND  SOMEONE  ELSE. 

Our motel has mini splits (heat pumps) with no backup. they work down to -5 , prolonged temps at -10 and high winds they could not heat it above 65. That was 2 nights at -10 and high in the day was 0, 20+ mph winds,