I don't see banana juice as an option (and thank goodness for that!) The best juice is peach juice, it's good cold or hot any can be mixed with tea nicely.
I used to enjoy drinking a glass of pink lemonade while my grandma and I played scrabble. At the time, it was one of the tastiest things I got to consume, so I have very fond memories of it.
So, in conclusion, I think pink lemonade is probably my favorite juice, not sure about it being the best though.