Pai and the associated restaurants are the best spots for real authentic Thai food. I haven't had a bad meal. My faves are the Pad Gra Prow, Chiang Mai Noodle Soup, Satay, Squash Fritters. These are the original group of people from the original Khao San Road (before the split) and Sukho Thai. All amazing and never disappoints. I recommend making reservations or walk in on a non peak hours. Otherwise you may wait up to an hour, depending when.