All of them.

But the one I like the most is Parametric polymorphism because it tends to make algorithms generically available to anything.

And the one I like the least is subtype polymorphism due to it's reliance on inheritance with all it's attendant problems. The exception being for the sub-genre of "interface" polymorphism. Which doesn't really exist in C++. However when it does exist such as in languages like Go, Java, or C# then it fixes almost all of the problems that tradional subtype polymorphism has by taking inheritance completely out of the picture.