1900 Park Fare was a slightly calmer atmosphere and you get to talk to face characters. Alice and the Mad Hatter are wonderful. Both are good in terms of food and interaction. Did both with two adults and we were not the only ones in either with no kids.
We've done both for anniversary celebrations. When we went to the GF it was Cinderella and Prince Charming, and I can't remember which characters were at the Crystal Palace, but GF was more calm, less chaotic. Food is great at both places.
Really, I would do both! I've done the breakfast at 1900 Park Fare and it was great. I've had lunch and dinner at Crystal Palace -- fantastic food -- and I'm going to that character breakfast on my next trip.