I've done all three plus the AquaCat. I did the T&C Explorer vs. Aggressor, but we were in sight of the Aggressor for most of the week. I'd rate them as follows:
1. Saba/Statia Explorer- great diving with no company to bother you
2. T&C-either boat-also great diving
3. Explorer I-Good if you get to SanSal, Otherwise a distinct fourth
4. AquaCat-Most comfortable boat, but average diving at best. The north end of the Bahamas isn't as good as the southern portion IMHO.
All of the boats provide luxury diving except the CEI is a bit older and rough around the edges, but the price is much better.
All including the AquaCat put DMs in the water on every dive. I'm a single diver and did not have any problems getting a good buddy, and I'm rather picky on buddies. I'd start by diving with the DM and watching the other single divers. Then I'd try to "pick one up" that I liked (dive-wise!!).
If you're considering Nekton, I'd review the threads on SB very carefully before making a decision. Enough said.
PM me if you want more info.