We have used several of the kid's clubs....WL, AKL, BW, and the Poly....and I think my kids favorite one was the Neverland Club at the Poly. Overall though, my kids found them all to be pretty comparable. There just seemed to be more for my kids to do there but again, when they were there, they were younger than when they stayed elsewhere. I don't know anything about the Contemporary's club. I didn't think AKL's club was that great and neither did my daughter.
I'm not sure now, but the Neverland Club used to be more expensive than the other clubs too.....I think by $2/hr more. So you may want to check that out if that is an issue.
Also, there is a definite plus about using the one in your own resort. The convenience is really a big issue for me. As long as there are no major negative's concerning the Contemporary's club, I'd go for that one.