They're the best in my opinion. It's fast, therefore if the date isn't going too good, you don't have to stay there for too long. It's cheap, so if you decide to pay for her, you won't have to spend much, and you won't be used for your money by a possible gold digger. Tables are small, so you're closer to each other, which is good. It's not formal, so you don't have to maintain a level of etiquette and be more relaxed.
In my opinion it's the best spot for a first date.