We have been to all the restaurants, but no counter service. Here's our picks. All but Mama Melrose are in our review of dining 2010 (link at bottom).
I think Hollywood Studios is a park where timing is important. You have to get there early to ride and/or get fast passes for Toy Story to avoid long lines (hour+). Shows are on a schedule. If I only had 1 day, counter service is a better way to fit things in. But we go 2 or 2 1/2 days. If you want a nice dinner and don't mind ending HS a little early, you can take the boat to the Epcot area resorts (Boardwalk Inn, Yachtsman, Beach Club) and have dinner there or at Epcot (if park hopping).
Brown Derby -- The grouper with beets entree was on par with the best seafood entrees I had elsewhere at Flying Fish Cafe, Narcoosees, California Grill, and at home. The soup was outstanding (a brie cheese and oyster soup).... unique, lots of oysters, delicious! I see a lobster bisque on the menu now... Returned for lunch and the steak filet was very good, not the best, but very good still. Service was great both times. If on the dining plan, it uses 2 credits so that may bother some.... But if going here for the fantasmic package, appetizers are included even on the regular dining plan (not deluxe).
Sci Fi Diner -- the best thing here from my experience and what I read are the simple stuff -- burgers, onion rings, fries, etc. Fun for kids. This is our lunch place.
50s Prime Time -- This is more like good quality 50s diner food. It did the trick. Fun place and decor. We enjoyed our food but be warned about giant size desserts! If you are not a big dessert eater... you could easily share a dessert between 2, maybe 3 people. The milkshakes are to die for... I've only had 1 just as good (Dumsers at Ocean City, MD Boardwalk).
Hollywood and Vine -- Go for breakfast only.... and only if you have children 6 or younger. The characters are a lot of fun -- they dance to Disney Jr. songs with the children, much better than the usual table greetings (they do that too). Breakfast was basic, but good. Lunch and Dinner food was comparable to your truck stop budget buffet place (like Golden Corral, Country Buffet).
Mama Melrose -- went here in 2009. Won't go again. Just a very basic chain store - like Italian place. It would be good if we wanted the Fantasmic Package and only wanted to use 1 dining credit. That's about it. Food was ok.