Yup, Harvard has more than the others. But, I'm a member of both Harvard and Westford... there are a few features of Westford that make it worth it to me to have two memberships at once:
1. It is quieter, particularly on a weekday, for times that I just want to be the only one there and concentrate on sighting in a new rifle or something. (If no one is around, I can walk back and forth to the targets all I want to examine the groupings and not have to worry about annoying anyone by making the range cold every 5 minutes.)
2. I can put the target stands anywhere I want (for the pistol range). At Harvard, they have to be by the berm. Of course, Harvard has both 7 yard and 25 yard pistol ranges to help out with different shooting distances, but I often like to put the targets at precise distances other than 7 or 25 yards (to experiment with where my bullets impact at various distances, see how the group spreads at different distances, etc.)
3. From the rifle range, I can shoot at 25, 50 and 100 yards without having to switch ranges. At Harvard, if I sight in at 25 yards and then want to shoot it at 100, I have to pack up and drive around the corner to the 100 yard range.
Westford also has larger target stands including one that's designed to hold bottles in front of the berm (at Harvard I'm placing the bottles on the berm).
Either (or both!) would be an excellent choice.