My kids love both! My husband dislikes both (he cant give me a reason). Neither one are my favorite I am neutral.
ohana's has Mickey, Pluto Lilo and Stitch. Breakfast is served family style. The characters do a little dance in the middle of breakfast and they give the kids instruments to use. very cut!
1900 park fare breakfast has Mad Hatter, Alice and Mary Poppins. Usual buffet.
both restaurants are very busy and loud. We have never gone to either without waiting a long time for our ADR (in slow season). Ohanas is a little more laid back and themed (IMO). 1900 Park Fare is a little more cafeteria looking.
We have done both and liked 1900 much better however I have heard others love Ohana. We thought the characters and food were both better at 1900 however our DD loves Mary Poppins.