I like Fantastia Gelati in Fantasyland - you can have a nice coffee and / or an ice cream and sit outside. It's usually fairly quiet. If you time it right it's a good spot to see the parade! Cowboy Cookout is a good spot in Frontierland for a coffee, and sometimes spontaneous character interaction. Also Casey's Corner is a good spot for people watching, but can get busy!
If you are talking about counter service for a meal - it will depend on what you prefer to eat, as they all do different things.