Ah, fun topic and it's been so top of mind lately for me. I'm gonna say 1/2" to 1.5", yet I can wear a little higher sometimes. Like KKards just mentioned, sometimes it has more to do with the pitch of the shoe than the height.
My whole issue (without droning on about it like I could, lol) is that I have tendinitis in my ankle and I think I may be getting a little arthritis in my toes (God, I sound like such an old lady) so just this year I've figured out really good low heeled shoes pretty much every day is the key for feet happiness! Luckily with AGL expanding, this is becoming easier!