The water temp and diving weather in the ABCs might be a bit nicer in the summer, but it will also be much warmer and more humid above water so there's a trade-off. Winter will probably get you more pleasant conditions on land except for more rain, and rainy season bugs. But an advantage of the ABCs is that if you're looking for a place to go in the winter, the water will be warmer than a lot of other destinations plus you're less likely to have lousy diving conditions than some other places in the Caribbean.
Are you really looking for someone to hook up your gear (which most serious divers seem to hate) or just more to avoid slogging gear around? I know I certainly don't mind an op that carts my gear around and has it on the boat for me, but I'm not crazy about them actually hooking it up and try to avoid that. (If you actually NEED someone to hook up your gear, you should address that - as even if you want to let someone hook up your gear you really need to check it over anyway. And if you're looking for a buddy other divers, or at least the ones you'd want to buddy with, will probably be unimpressed by someone who relies on having their gear set up for them.)