[Bozeman]

For a table of ten players who play showdown poker with any hand (no betting or folding), the hands are ranked according to showdown percentage against 9 random hands, and the median best is (from pzhon, etc.) best ~7%. There are 89 hands in this set, and for showdown against 9 random hands these are 99-AA,AK,XTs for 88 hands with AQo on the bubble.

For a more reallife answer, you would need to specify a complete ranking of hands. As others have pointed out, this is difficult or not too meaningful. In addition, knowing the median doesn't help much because much of the coolness of poker comes in the variations (like Ak and qq being dealt together).

Craig