Of the four resorts, each offers something a little different.
LCBR - I love the place and have been back multiple times. Excellent food, outstanding dive operation, rooms are reasonably nice but not what I would consider "upscale". Multiple boats and large dive groups can occasionally make it feel slightly hectic leaving the dock in the morning, but otherwise really well set up dock and storage arrangements.
Pirates Point - Haven't stayed there, but the draw seems to be the cozy atmosphere and eating the meals prepared by the owner family style. I believe they don't do afternoon dives and I think you will have to wade out to get on the boat each morning. Seems to be comparable in price to slightly more expensive than similar packages at LCBR. Dive operation gets good reviews, but they only have one boat that I am aware of.
Southern Cross Club - Have not been there, but it seems to be a slightly more luxurious version of LCBR with comparable increase in price. The accomodations appear to be more upscale but otherwise is very similar in operation to LCBR from what I have read.
Paradise Villas - This is the budget option. You would either have to prepare your own meals or go to the one restaurant on the island or one of the other resorts to eat and pay accordingly. You would dive with Conch Club from the LCBR dock (either walk or ride in a van). They leave half an hour before the LCBR boats to avoid crowding or confusion at the dock, but otherwise their dive op is very similar to LCBR. Leaving early gets you first choice of dive sites, but that is rarely an issue anyways...and for those like me who aren't early risers, it means getting up another half hour earlier while on vacation.
I am sure I haven't given the other resorts enough credit for some things that maybe differentiate them from LCBR, so others who have been there are welcome to step in and add anything I may not have pointed out. I have weighed out the pros and cons several times, and LCBR always seems like the best balance of affordability and quality for me, but if luxury is more important, maybe SCC is your place...or if budget is more important and you can't find a discount package at LCBR, maybe Paradise Villas is the ticket. And if you like the cozy family dynamic, Pirates Point may be your deal. As Bruce pointed out, no matter which one you pick, they are all good. So I suspect you will come home happy and satisfied with your choices no matter what you decide.