I think they all have their own advantages and "personalities." I've only stayed at 2 different concierges (Poly and YC), so I can only tell you about those two.
Poly--excellent food in the lounge (lots of choices and good stuff for picky eaters), very friendly staff, casual atmosphere, lounge has great view of Cinderella castle so you can watch the fireworks, entire Hawaii building is concierge access only, our lagoon view room was incredible (it had a terrific view of the castle, Contemporary, and GF--#1512), very family friendly
YC--food in the lounge is a little more upscale, so some meals wouldn't be as good for picky eaters, very friendly staff who were very helpful, upscale (but still friendly) atmosphere, lounge is very elegant, entire 5th floor is concierge access only, lots of adults and business travelers, but still good for family
I would stay in either concierge again without a doubt. Hope this helps!