It's the YMCA. The original gym/fitness center. Ok, I mean in modern times--like the last 120 years or so. If you have kids and live in the community it's worth belonging to the YMCA just for the discounts on kids activities and the chances for involvement. But the YMCA in the Phoenix area also has several surprising features in their workout center not found in other places.
I belong both to the YMCA as well as a corporate gym (LA Fitness). It's surprising to me that YMCA has implemented the FixLinxx System while the sales reps at LA Fitness have never even heard of it. FitLinxx allows you to keep track of your cardio and circuit strength training by first logging into a central console when you arrive, then entering your PIN at each machine as your progress through your workout. The system lets you track your progress in a convenient way, keeps you on the straight-and-narrow for range of motion and speed of reps, and even bitches you out if fall short of your goals for training frequency or sets/reps for a given time. I have found it to be wonderfully helpful in my program. Again, LA Fitness does not have anything like this system, but most YMCA's in the Valley have FitLinxx fully implemented. And the family rate for the YMCA is attractively low considering it includes things like child care during common workout hours.
This location tends to have a lot of older members working out throughout the day, which can get embarrassing for people 20-30 years younger (like me) who can't keep up with them.
The biggest drawbacks for me (and reasons why I joined another gym) were the limitation in hours (close early most days and at 3 on Saturdays) and the location (it's a 6 mile drive for me). Also the facilities are often not as well-kept as they could be. At times nearly a third of the treadmills will be out of commission.