The Borgata reputedly has the loosest slots and the best poker games in AC. Personally, I don't like Borgata - it's inconvenient, the staff is snooty (and I don't understand what they have to be snooty about) and it just has a cold character about it. But I'm in the minority, as many people seem to love it.
As to room comps, Harrah's gives those out like candy, but at Borgata, it is reputedly difficult to get rooms comped, but I believe I read this elsewhere (or maybe it was here, I can't recall) that there is a trick to getting rooms comped, or at least, this is what one woman did - actually as i think about it, it's kind of complicated to recall precisely, but she would go and play $100 worth of slots and couple times a month, and after 4 months, she got rated as room-worthy and started getting offers. I will try to find that information and post it here in this thread, if I can find it again.