This is clearly subjective, etc, etc.

That said, we have eaten at every restaurant in Epcot (except Spice Road Table that we are doing in Aug, and Tutto Italia that we're not really interested in) and OUR personal favorites are
Via Napoli and Le Cellier.
At some point this board seemed to turn on Le Cellier (when they made it 2 TS??), but we have enjoyed it every year since 2005 or so.
Via Napoli is probably our top Epcot choice these days. EXCELLENT pizza. Some complain that it's loud -- it's certainly not QUIET, but if I hadn't heard that here, it's certainly not something I would have complained about.
Some other ones we like...
- Monsieur Paul was good -- had a couple of "date nights" there
- Biergarten is fun, but far from best food.
- Teppan Edo is always tasty, but not that different from any other hibachi style restaurant that might be in your neighborhood.
- Tokyo Dining is solid, but again not different from places we have in our neighborhood.
- La Hacienda is nice if you like Mexican food.
There are places we've done once and have
no desire to ever do again:
- Coral Reef
- Rose & Crown
- Restaurant Marrakesh
All the ones I didn't mention we find "ok", but we'd rather go back to our favorites or some of the others we like than do them again.