You really can't go wrong. It honestly depends on your tastes and what you like. The only place I wouldn't recommend is Coral Reef. I think it's dated, overrated and the food is okay, but nothing special.
Off the top of my head, here's the best ones at EPCOT:
Biergarten: German food. We really enjoyed the food, selection and atmosphere, however, it's on our "did it, can live without it" list. We went, we tried it and enjoyed it, but it's not something we can't wait to go back to. It's traditional German food - wursts, sausages, etc. If you're picky, you may not like it.
Rose & Crown: Okay food, great atmosphere. Probably your best bet for picky eaters as it has a lot of steak, fish and chicken dishes. Not overly seasoned, decent-sized portions and it's an EPCOT staple.
Teppan Edo: Many would argue that if you have a Benihana nearby, Teppan Edo is just like it. True, but we've never had a bad meal here. The food is outstanding and fresh... and the menu is filled with your traditional Japanese fare. I always recommend Teppan Edo and we can't wait to go back.
Via Napoli: It's pizza. We found it to be overrated, but it was still good. Go with lower expectations than the "amazing, best pizza you've ever had" reputation it's gained and you'll really enjoy it.