House of BEST..
I moved to Los Angeles from Boston about a year ago. HoS was the first shop I went to to get my weekly comics fix. Not only are they extremely helpful, friendly, and courteous, but I have always been able to find anything I was looking for there, and usually for less than what I'd pay at any other store. You'll also occassionally spot a mild-mannered comics celeb there (Chuck Austen, Steve Niles, or Joss Whedon) buying their books. Parking is never a problem, and they have unbeatable sale events, as well as FREE bags and boards w/ every issue you buy! Staff is comprised of avid comics fans, but they are never snooty and always have great, reliable recommendations when you need that extra fix!
Location may not be convenient for some, but it's worth the trip.