Oh, I love Animal Kingdom. This is not the general consensus, though.
I have an annual pass. so I can come and go to all of the parks as I please, so I'm not wasting any days on passes. I go there to see the animals, get on Everest five or six times, ride Dinosaur and Primeval Whirl at least once each, and get on the Safari a few times.
This is the park that I do the least often, though. Here are the reasons:
1. It tends to be the hottest park. While this is good in January or February if you get a cold week, it's not so good in August. So usually, I'm there for 2 weeks in August but only do it once or twice. If I go in June for a few days, I do it on the last day out of tradition
2. It's the largest park, meaning that it's very spread out. There's a lot of walking, which a lot of people don't like, and to get to Raffiki's planet watch, you have to take the train. It's easily been two years (about five trips) since I've been to Raffiki's because of this. It takes a lot of time to get over there.
3. The main attractors are the thrill rides. There are no dark rides and only one kiddie ride. If you don't like thrill rides and don't care about seeing the animals, then there's not a lot there for you.
4. It's kind of the after-thought, though they are working on an Avatar section. Personally, I think that a Mythical Creature section featuring an Avatar attraction or two is a better idea. At least they are adding to it, though.
5. It's the youngerster out of the bunch. It's only been open since 1998 (it's younger than me! Only park besides Blizzard Beach that is), so it hasn't had the time to fully develop the way that the other parks have.
In order to do Animal Kingdom and not be miserable, you have to know how to do it. We had friends that went and never got out of Camp Minnie Mickey. We fixed that the next time when they went with us. You also can't plan to spend eight hours there. You have to plan to go, do what you want to do, and leave and go to Magic Kingdom, Epcot, or Downtown Disney.
So yes, I find that it tends not to be a "favorite". Most families I talk to skip it. But you have to have reasonable expectations for it.