どっちも好き！だけどAの方がもっと好きって英語でなんて言うの？

1. "I like both types of chocolate, but I like milk/dark chocolate more.
   Types - flavors of chocolate. For example, there is milk, dark, and white chocolate.

   More - Meaning to a greater degree. (Example: "I like Spiderman, more than I like Batman.")

   2. "I like both, but if I could only have one, I would choose A." In this sentence, you are explaining that you like both options, but that if you could only eat one, you would pick A.

"Both are nice but I prefer A more"
This sentence is explaining you enjoy both 'A' and 'B' but you prefer A, when using 'prefer' this is used when explaining that you favor/like something more than another.
"A is my favorite but they are both good"
'favorite' is referred to having preferred/like something more than anything else, Something 'at the top of your list'

When you want to express to someone that you like both types of chocolates but like the other more; then you may express this in the following ways:
-I like both, but I like A more.
-I like both but if I really had to choose, then I would go with A

To prefer something means that you like something more than something else.
I like cake, but I prefer cookies.
I like both, but I like A more.
I like both, but I rather __.