I have thoroughly enjoyed my stays at the GF, YC, and AKL. As a reference point, I stayed in a garden view room at the GF in 2000, a lagoon view concierge room at the YC in 2002, and savannah view rooms at the AKL in 2001 and 2002.
The GF is my favorite Disney resort. I love the convenience of the monorail, the elegance of the resort, and the wonderful decor of the rooms. I truly felt special and pampered during my stay at the GF.
The YC was wonderful as well. It was very quiet during our trip, which was wonderful. The proximity to Epcot (and the convenience of the path to MGM as well) is a wonderful perk. The new room decor at the YC is also super cute. And of course, there is Stormalong Bay, an incredible pool complex. The only slight improvement I wish they would make is adding a quick service restaurant with longer hours (where you could get a quick bite to eat and refill your refillable mugs). Hurricane Hana's and Beaches and Cream aren't open super long hours like the quick service restaurants at the other WDW resorts (which left us a bit out of luck for breakfast, so we walked over to the BoardWalk Bakery).
The AKL is another favorite resort of mine. It has an incredible atmosphere, and there's just nothing as neat as seeing live animals right outside your balcony. The theming here is top notch, and you really feel like you've escaped when you're there. The only downside is that the AKL is a fair distance from all the theme parks except the AK. We never had to wait very long for a bus, but the bus rides themselves were sometimes pretty long due to the distance we were traveling.
Really I don't think you could go wrong with any of these three resorts.