The letters don't really hold any importance anymore to me as they once did. It's all about the functions for me.
But with that being said, I guess to answer your question, i'm gonna have to say N.
I value Ne/Ti and it's hard to really separate one from the other for me because they make me who I am and I value my perspective greatly.
I guess though that if I had to pick one i'd pick N because it nothing else i'd still like to be able to see multiple possibilities for things. I mean one can be "Thinking" but if they don't really have the right function to support it or dominate it then it's kind of useless, at least for me. (Not knocking any other types i'm just basing that comment off of my own values)
At least with INTUITION I can have my head in the clouds and i'd still be creative. So ultimately if I had to choose one I guess it'd be that.
I don't know how to say which of my functions is most important without mentioning that it's pretty much useless without any support...
I guess I'd go with intuition, though, since Ne is my dominant function and lends the most to my outlook on life.