Worryingly 2 people have mentioned Malta , I was intending to go there in November for a short break.
A couple of people i know from Glasgow did a round the world bike tour about 10 years back; Canada, USA, NZ, Australia, Vietnam, Burma, India, Pakistan, Iran, Turkey... etc. According to them, by far the friendliest locals were in Iran.
I don't think there's anywhere I've been that i wouldn't go back to.
England. How could I forget ENGLAND! .
Russia, China, US.
+1 for Malta