DW and I have made it a goal of ours to sample all of the concierge offerings at WDW at least once. Disney got us hooked on this initially by giving us a free upgrade at WL a couple of years back. Since then we have had at least one night (usually that's all we can afford!) at all of the concierge resorts except for Yacht Club and Polynesian -- but hopefully we will take care of that in the next couple of years. So far, we can unequivocally say that the concierge at AK was our favorite. We also enjoyed WL, but since then they have actually built a concierge louge -- when we were there it was just some serving tables set up on a walkway above the lobby, with some tables and chairs scattered around on that level. So I guess we need to try it again some time to see how it's changed!
We also agree that our least favorite concierge (at WDW) was at the Grand Floridian -- the offerings were good, but we always felt that the staff were "hovering", watching for us to take a mis-step or something.
I will say that our worst-ever concierge experience was at the Grand Californian at
Disneyland Resort. My daughter and her fiance had used his points to book a two-night stay, and listed DW and I on the room with them. DS, DDIL, DGS (6) and DGD (2) were staying at an off-property motel. During the day the two grandkids got a bit tired, so DW and I volunteered to take them up to our room for an afternoon break. We went with them into the concierge lounge to get some cookies and a soda. They were well behaved -- actually they fell asleep after one bite of cookie, so we just stayed there, DW and I reading the paper and snacking. The lounge was nearly empty, so we didn't see an issue.
Some staff person from the concierge desk came in and started asking us who we were and in what room we were staying. She left, apparently to check on us, and on returning she said, "there are no children listed as occupying that room, so they are not allowed in the concierge lounge. This lounge is for the privilege of paying guests only." I couldn't believe it!

Here I thought the whole idea of concierge was to provide service. But I guess this CM saw it as her duty to be the "concierge enforcer" -- more like the "concierge Nazi."
Technically, I suppose she was correct, as our grandkids were not staying in the room; but it was uncomfortable to be made to feel like some kind of a thief over a couple of cookies!