I have stayed at all of them....well, not actually 'stayed at' YC, but dh did and we checked out his room and such. I prefer BW, but that's my home resort, so I'm a bit predjudiced. I like YC/BC...prefer BC to YC...a bit airier and light. I am one of the few people that isn't crazy about SAB. You have to leave the pool area, cross the public sidewalk and then enter the shipwreck pool slide. The pool area is huge...really hard to keep track of your kids, especially if they are using that pool slide.
I love BW. Yes, it has that 'creepy', 'scary' clown slide. BUT, my dd has loved that slide for almost 8 years now...since she was 10. She loves yelling 'clown barf' as she exits the clown mouth at the end of the slide.
I like the easy access to both DHS and Epcot from BW. It's a bit closer to Epcot from BC, but further from DHS.
They are all pretty similar except for a few things. Transportation is about equal.