Too many to list honestly. It also depends what you are looking for in a PH. Are you looking for a public establishment that has full bar service? Are you looking for a straight PH, ala Ames in the Hustler? (no booze, no food, just pool. This is Ames mister!) I've had the luxury of being all over the country, thanks to the military and have seen some very good PH's. Here's my short list...which isn't too short. If these are in any order, it's from East-West coast...not in precedence.
Chelmsford Country Club USA, Chelmsford, MA - Huge establishment, owned by Dave Cunha (sp?). Three different rooms with tables. If I remember correctly, over 60 tables. Full service bar. The last time I was there, they had Brunswick GC III's.
Snookers Bar and Grill, Providence, RI - My personal favorite pool hall, for a couple different reasons. The atmosphere in this PH is IMO, second to none. Owned by Steve and Regina Goulding, the equipment, (all Brunswick GC's, with one AMF in the back), is kept in great condition. Of particular note, the food here is excellent. Mrs. Regina Goulding makes something from scratch every day.
The Gold Crown Billiards, New London, CT - 16 Brunswick GC III's, 1 12' Brunswick Snooker table. A cut and dry Pool Hall. Vending machine drinks, no food service. Just pool. Equipment is kept in very good shape; the tables when I worked there were being done by Mike Xiaros and his crew twice a year.
Amsterdam Billiards, Manhattan, NYC, NY - I have NOT been to the new Amsterdam Billiards. I can only speak about the old Upper East side venue, which has been closed. But from what I have read, the newer place is very nice too. Also, if I'm going to pay homage to places now since gone, I have to mention the old Chelsea Billiards (also in Manhattan), Chicago Billiards, (New Haven, CT), and Jack and Jill's (Glenn Burnie, MD). Those locations were great action spots during their heydays.
Big Daddy's Billiards, Baltimore, MD - 6 Diamond's, 10 GC's. Peter Burrows owns and operates this fine establishment. Player friendly atmosphere, and great equipment. Last time I was there, about 6 months ago, Mr. Burrows was in the process of expanding into a neighboring shop in order to give him more space for tables.
Action Billiards, Salisbury, MD - Great tournament room located on the eastern MD penninsula. IIRC, the main room had about 10 GC's, second room had 8 GC's, and they also had a TV table pit at the time. Extensive pro-shop as well. Not sure if it is still open or not.
King Street Billiards, Fayetteville, NC - Awesome PH owned by Danny Odom. 25 tables, (15 GC's and 5 Diamonds, and 5 Barboxes), great food, great atmosphere, and great staff. If you're in the area, you must visit this room.
Speakeazy Billiards, Sanford, NC - A short drive from Fayetteville gets you to Sanford and this very unique pool room. If you're a fan of a classically decorated PH with antique memorabilia, this is the place for you. Limited bar and food, but excellent equipment. Another must see.
Grady's Billiards, Lexington, SC - Grady Mathews owns this joint, so that should tell you right away that the equipment, all Diamonds, is well kept. There are 8 7' Diamonds and 13 (IIRC), 9' tables. Grady is usually on hand as well to relay one of his numerous stories of life on the road, life as a pool player, as well as some other, off topic stories.
Marrietta Billiard Club, Marrietta, GA - Johnny Archer and Kim Davenport's room. Over 30 tables in very good condition, (c'mon, what'd you expect out of those two), great food and a fun atmosphere. Great room to go to a tournament at. Full service bar as well.
Mr. Cue's II, Atlanta, GA - One of the more well known pool halls in the Atlanta area. They recently replaced all of the Kim Steele pool table's with GC IV's. Full service bar, and the food is ok.
Diamond Billiard Club, Chattanooga, TN - 16 Diamond Barboxes and 4 Diamond 9' tables are in this establishment. The equipment is always top notch, and the food is even better. One of the owners, Davey Crockett does the menu's for the place and always has a "from scratch" daily special. No matter what it is, it's delicious.
Bogey's Billiards, Houston, TX - Great room located just north of Houston International Airport. IIRC, about 24 tables. Good atmosphere, well kept equipment. Didn't try the food there, but the staff was pretty friendly. Both times I went there, there was a golf game going on.
California Billiard Club, Mountain View, CA - Chet Ito (sp?) owns this room and, the last time I was there, (2004), the equipment and food was great. Very accomodating tournament room as well. I believe they have 35 or so tables. (not positive, could be less), a 12' snooker table, and 2 heated Verhoven Billiard Tables.
I've been to many other pool halls, but these are the one's which stick out in my mind as being some of the best, whether it's because of sentimental reasons, good action that was there, or just it being a plain ol' great room. Hope this answers your question...and no. I couldn't pick just one as being "the best". My favorite I wouldn't classify as being any better than the others. They each offer their own take on what a great pool room should be and should offer to the players.