I think this really comes down to preference and how it fits in your plan.
1900 Park Faire is a buffet. My family likes it, other people don't. We love the Stepsisters and Lady Tremane. Hilarious, especially for my DS12.
Teppan Edo is different in that they cook the food right in front of you and the chef does sort of a show with his/her knives. I can't think of the chain that does similar cooking, but we have a restaurant here in MN called Ichiban's and it's the same type of set up. Here the food is a more a la carte than all you can eat.
1900 Park Faire is at the GF; Teppan Edo is at Epcot. Which works best on the day you are thinking? My thinking is if you are at MK that day and have to hoof it over to Japan to eat, that's a lot of travel time to get over to Teppan Edo just to eat. In that case, 1900PF would be more convenient.
As I said, it's all personal preference.