For us, CRT princess interaction was not any better than Fairytale Hall. There were just a lot more princesses. The experience of eating in either castle is a very good one for the atmosphere.
BOG will be significantly cheaper. If you have never eaten in either, I would suggest BOG just so you can see the castle and because it is less expensive.
Eating at CRT is very nice for a 5 year old, though (girl, I assume?). My daughter was 6 when she first went to CRT. It was very special for her. For me, I thought it was overpriced for what it was (even more so than BOG), but that was the one table service restaurant she asked to go back to.
Are you going to Epcot, too? If so, I would do Akershus there and BOG at MK. The princess interaction is just as good as Akershus and it requires half the meal credits (if you are on the dining plan).