Honestly, just a field where people show up. Unfortunately, I live about 2-2 1/2 hours from any "organized" field, so I feel giddy if I get to play with more than 4 or 5 people in the woods somewhere. Fields pop up now and again close to where I live, but I usually know more about paintball than the owners, and the fields aren't much to speak of. Then, 3 months later, they are gone.
BUT, if I had some choice:
1. Friendly Staff.
2. SAFETY FIRST (maybe this should be #1).
3. Variety of fields (Air,Speedball, Woods, etc. I like them all).
4. Quick turn-around times on games.
5. Reasonable Prices ($80-100 paint is not reasonable for junk paint, sorry).