I agree with all of the above. In the parks:
MK:
Cosmic Ray's has a good variety with burgers, barbecue, wraps, sandwiches
Peco's Bills has great burgers, taco salads, and condiment bar
Columbia Harbor House is the place for fried fish (I personally like the tuna sandwich ... which I discovered the day we did the KTTK tour)
EPCOT:
Sunshine Seasons is great for variety
Countries at EPCOT are really the best way to add variety to your counter service experience... I love the Yakitori house in Japan, the Tangierine Cafe in Morocco, the Lotus Blossom Cafe in China, the Cantina de San Angel in Mexico... I have eaten at all these and love them all. Then there's Kringla bakery (Norway) and Boulangerie Patisserie (France) for sandwiches and deeeeeeelicious desserts!
AK:
Flame Tree... love the smoked chicken. Yak and Yet CS has great Asian inspired meals. I had the shrimp and noodles last year... yummy!
Studios:
We always end up at ABC Commissary because it is the only indoor/air conditioned place with plenty of tables. Not really my favorite, but I always get overruled about trying something new. (Would love to hear opinions on the other CSs in the Studios.)
Best resort CS:
Port Orleans Riverside!