Having stayed at all 3 at one time or another I can only say that they all offer their own ambiance. Their locations are also very different as well.
Just depends on what you're looking for.
BC probably offers the best location as the Epcot resort area is a great area to stay in. You're a boat ride or even a walk away from 2 parks plus there's lots of eateries, shopping and entertainment within walking. The accommodations are nice although we do find the rooms at BC a bit on the small side (unless you stay at the BCV). BC is also the most expensive of the 3, but of the 3 you can't beat the location.
AKL is a very unique resort but to FULLY appreciate it's atmosphere you need to have a savanna room which is more expensive than the standards. There are many lookout areas from the hallways but if you don't have a savanna room, you can't fully take in what it has to offer.
Yes, there is construction going on and being that they are building an entire new section it will probably go on for quite a while. The resort does have a cozy feel to it as well as great restaurants. It is located way out there though and although it is a quick bus ride to AK, it does take a little longer to get to the parks than it does from any of the other resorts plus bus is the only way anywhere. No walking or boats to parks or food/shopping areas there (other than those located inside the resort itself).
SSR is a rather large resort and is located probably the furthest from the parks but it is right across from DTD. You can take their boat to DTD or walk from some locations. The rooms are very comfortable and the resort is nicely laid out with many amenities. And even the studio room has a kitchenette area which we find VERY convenient in our room at WDW.
We've actually enjoyed staying at all 3 of these resorts and would stay at any one of them again although SSR seems to have the best rates that's where we've been ending up lately.

...just depends on what type of experience you're looking for.