We've done both in one trip and are doing both again during our June, 2007 trip.
The dinner at the Liberty Tree Tavern is turkey, ham, mashed potatoes, veggies, mac and cheese, rolls and salad. The last time we were there, our dessert was pie and ice cream. I think it may have changed though.
The service at the Liberty Tree Tavern was great. The servers were very attentive and were quick to remove and replace the dishes and food.
The characters at the Liberty Tree Tavern seemed to interact with us more than at the Crystal Palace. My daughter was wearing a cowboy hat and Goofy got it and placed it on his head and did a little dance with our daughter. Chip and Dale came to the table too. Chip kept pointing to our son's roll, letting him know he better start eating. Next thing you know, Chip had a roll from our basket and had stuffed it down into his costume. Our son thought that was so funny.
I think you would be pleased if you were to choose the Liberty Tree.