Crossfit is not like Ballys or 24 hour fitness, assuming you know that:
Why I chose 702
-proximity
-reasonable pricing- some other crossfit gyms in the area are twice the price or more (I paid for a year which earned a discount)
-good website- blog with WOD posted daily
Some specifics
Community- is pretty active. They have group events, participate in local fitness events like 5k runs, and organize group orders for supplements and grass fed beef. People are very friendly. The average level of fitness of the members is higher here then where I've been in the past but coaches/other members are very nice about me taking 5 times longer to finish.
Facility- much better than some boxes I have been to, its all new/well maintained, and they have a lot of it so needing to share/run heats is minimized. Running goes on outside, everything else is inside which is spacious enough.
Coaches- are nice and knowledgeable. If anything I wish they were less nice/yelled at me more.
Programming- more 2 part wods, like lifting followed by a short metcon, as opposed to 35 minute plus gassers. Lots of running.