We've been to both (for breakfast). 1900 Park Fare only had Cinderella (for a princess). She was joined by Fairy Godmother, Prince Charming, Perla, and the other mouse (I forgot her name) Akershus had Mulan, Snow White, Jasmine, Belle, and Aurora when we were there.
As far as meeting princesses, Akershus has a greater variety. Both are the same for princess/character interaction. We've been to several character meals, and the interaction is always the same. The characters make their rounds and will all make an appearance at your table. The "face" characters (ones without masks) chat with you, sign autographs, and take photos.
For food, we prefer 1900 Park Fare - it's a buffet with a much better selection for finicky eaters. Akershus has food that is brought out to you and served family style. Limited choices.
IMHO, if you want more princesses go to Akershus. If you're looking for a better meal, go to 1900 Park Fare.
Hope this helped.