My favorite bar in Lower Haight is the. My favorite bar in Lower Haight is the always happening Page. It's cozy and fun complete with pool and fooze ball in the back. It's cash only, so come prepared!
If you want a solid SF dive bar, The Page has everything you need: cheap beer (for SF, at least) with a decent selection, good whiskey, pool tables, and that perfect amount of dimness that says, "Welcome to a dive bar." Fun on any night, and rarely gets too crowded.