I eat a LOT of counter service when I'm at WDW.
Epcot has my favorites, thanks to the huge variety.
For years, the fish and chips at Yorkshire County (in the UK) have been an absolute must-do for me. TIP: Don't get tartar sauce from the outdoor display in 90-degree heat, it will make you SICK!
Recently I have been very impressed with Lotus Blossom cafe in China. I particularly like the Shanghai Chicken and Rice bowl - very tasty, large portion, reasonable price.
I always wind up eating at the Electric Umbrella. I usually get a burger, but they also have a good selection of other stuff. Mostly I like EU for the location - I love to sit on the upper level and people watch as the crowds flow through the breezeway.
The Seasons food court in the Land is very nice, with the best variety of CS food in Epcot. Quality is usually very good, too. The atmosphere is bustling, very much like the food courts in the Value and Moderate resorts.
Tangerine Cafe in Morocco is a great break from the ordinary, but easy on picky and non-adventurous eaters. Try the chicken and lamb schwarma combo plate, it's excellent. - and you can usually hear the Moroccan band playing across the way while you eat.
Make time to walk through the Fountainview Bakery for a dessert or sweet snack during the day. Many people miss this little gem, located on teh opposite side of the Fountain of Nations from Electric Umbrella.
And if you have time, walk out the International Gateway and visit the Fountain eatery, in teh lower level of the Dolphin. They have some great burgers, sandwiches, salads, fries, that sort of thing, and an apple-pie a la mode that is out of this world!