I’ve not seen enough of the world yet to pick a favourite but I loved the Riviera Maya as a base in Mexico. The people were friendly, great weather, fabulous cultural activities in between relaxation. Would go back in a heartbeat.
Second to that would be South Devon, have family there and been travelling there since I was about 4 years old on a frequent basis. I plan to retire there! I always feel calm and at one with myself there.