@evan Around 20C seems like a happy medium to me. Depends a bit on the house and the location of the thermostat.
We got a heat pump a couple years ago and I nerded out on the optimal settings to take advantage of Ontario's time of use rates (letting it dip a little lower during the evening, trying to get it just above our normal setpoint before the peak time of 7am). Was a fun little exercise but I don't think it really saved that much money.