I think it depends on what you're looking for. If you like buffets with lots of options and some characters that you don't get to see almost anywhere else then I would pick 1900 Park Fare's breakfast. If you like the basics (Mickey waffles, eggs, bacon, etc.) brought to your table so you don't miss the characters than I would pick Ohana.
I personally really enjoy both and have to do both every time I go. They both have good food and a good atmosphere.