Wow, probably THE hardest choice to make for a CS is at Epcot. The other parks there are a few that stand out....EPCOT....they almost all are wonderful.
Several have mentioned Sunshine Seasons....this is the place that has the largest selection and will probably be the easiest to find something for everyone no matter what their preferences are.... there is Asian food, soups, salads, sandwiches, hot items like rotisserie chicken, salmon and pork chops. There is a wide variety of "sides" to choose from mashed potatoes, salad, rice, carrots, etc. Wide variety of desserts too. There is also a grab and go that has sushi, quiches, sandwiches, etc.
Electric Umbrella (also in Futureworld) is a pretty typical burger joint, but also has chicken salad, sandwich and nuggets. I think there was also a veggie choice available here.
Then you get to the Countries!
United Kingdom.....Yorkshire Fish and Chips....delicious! The desert choice is only shortbread and it's packaged so not a favorite....if you don't have the dining plan where it's included, don't bother to pay for it. Save your $ for a sweet in France!
France....most people skip over Boulangerie Patisserie thinking it ONLY has sweet treats....but they have wonderful Croissant sandwiches and quiche too. There is also a cheese plate for those looking for a light meal full of protein! Of course, the sweets are excellent too!
Morroco has Tangierine Cafe which has Shawrma and wraps and meatball platters. If you're not sure about whether you'd like this food, a suggestion is to get one meal to share....if we like it you can get more, if it's not your thing, it's easier to toss one meal rather than more! I knew I would like the lamb, so this plan would be risk free for us, as if they didn't like it I'd take it along to another country to find them something.
Yakatori House in Japan has some rather Americanized Japanese food...nothing spectacular but good typical fast Japanese food. Teriyaki Chicken, Sukiyaki beef, tempura, curry beef. The sushi is pretty much California rolls, but it's prepackaged like you can get at some grocery stores, so not exactly high fresh quota.
America has burgers and chicken items, even a veggie and kosher meal. Nothing to write home about, but then again, if USA is your home, it's comfort food.
China's Lotus Blossom was ok....another Americanized menu....orange chicken that was way too sweet for me, but the kids loved it....Mongolian Beef with BBQ sauce was just to weird for me, but the chicken salad was pretty good. Potstickers were a bit dried out like they'd been sitting for a bit, and the egg rolls were too greasy for my taste.
Norway's Kringla Bakeri had several sandwich choices, soup, and salads in addition to it's yummy sweets.
Mexcio....this was probably the most disappointing of the CS in World Showcase. Living in Arizona we have some great Mexican food around....well, I'll have to wait until I'm home to get some. They have tacos, burritos, quesadilla, nachos, etc....but it really wasn't very good quality food and VERY Americanized. BUT....the servings are quite large so if you like American/Mexican food it's a good choice to share a meal.
So.....lots of choices. I highly recommend sharing meals so that you can try more countries' offerings.