There's not all that much to Kep. As a place to stay, I preferred Kampot which isn't too far away. Can't really rank these places, just completely different in size/feel/atmosphere. Rangoon is much larger and won't be as laid back. Vientiane is a small city, sleepy by SE Asia standards. Kep is basically not much beyond a village, Kampot is a small town. Both also sleepy.

Are you coming from a long distance or already in the region? I have the impression you are based in BKK, KUL or SIN.