Well...the boats are really large enough that you're not particularly stuck with anybody. So I think that in general you can probably find a compatible subgroup of people and have fun no matter who organizes the charter.
However, I have seen some differences in the Channel Islands cruises based on the makeup of the people on the boat. I went once with a dive shop where the owner was on the boat and so got a chance to influence very strongly the choice of dive sites where we dropped anchor. He was more of a hunter than anything else, so we ended up going to several sites I thought were right boring just so he could look for scallops. Also, he was concerned with the long drive back and so convinced the boat captain to come back a little early on the last day. Then I did another cruise with the wild and crazy tour organizer over in Santa Cruz and had a totally different experience. He is a marine biologist and brought along his microscope, then gave some fascinating lessons based on little stuff he brought up with him.
So...my suggestion would be to think about what kind of diving you like to do, then poke around at the different dive shops in the area and see which ones have the same kinds of interests for the cruise that you do. You're going to have a great time no matter who organizes the trip, but I think it helps if you all have the same basic objectives.
Bruce