The group got too ridiculously large, but I wouldn't have kept it at just the original three. Eric Bischoff added a lot by sort of 'leading' the group. Syxx was a good addition. Scott Steiner's betrayal and sort of physical transformation when joining was also very neat, but unfortunately, that happened when the group was starting to get really stale. Savage looked good as a heel in the group. Giant was a good addition, though he didn't last long (until he joined again in '98.) I think this might be the limit for me.
Dibiese, Vincent, Scott Norton, Disciple, Stevie Ray, etc. didn't really add anything to the group. I might list Bagwell there as well, because he played the arrogant part very good (possibly because he really was an arrogant ass in real life) but not all heels need to be a part of the NWO. It's possible to be a heel and play the part without being part of the main heel group so Bagwell could have done fine without them (not that he ever amounted to anything anyway.)