What is the most efficient way to choose a pivot in Quick Sort Algorithm?

[MoeketsiM]

Which method is better and more efficient than the other, to choose a pivot randomly or to choose it by selecting three indexes (index 0, index n/2 and index n) and taking the middlemost number between the three?

[Dormilich]

I think that there are several variants of Quicksort, which differ in exactly that: how to choose the pivot.

though in general (I have read) that Quicksort is fastest if the sub-lists are about equally large.

[dianagaby2002]

We were using the n/2 at univ.