I prefer
Caroline. I don't mind
Carolyn, but it doesn't sound as pretty and classic as
Caroline. It also sounds too much like carolin' (like the word 'caroling' without the 'G'). I hate it when people pronounce
Caroline the same way as
Carolyn. If you use
Caroline, your daughter might be called
Carolyn by mistake, but I don't think that it would happen all that often.
BTW
Carrie is a cute nickname.