I'm guessing you're looking for table service, yes?
Depending on the age of the child ... the best combination of food and the "fun" factor is probably 50's Prime Time. If he/she is a fan of old sitcoms (think Nick at Night), this would be my call.
Sci-Fi is one of the most atmospheric restaurants at Disney. I think you can have a better than decent meal there if you stick to simple stuff.