The best hand to crack AA is actually 78s (different suit from either of the aces). Probability says so. It also logically makes sense. against AA, it generally doesn't matter how high or low your cards are... no matter what they are, they're both smaller than an ace (if you have Ax, you are really screwed obviously). You basically need to pair both of your hole cards to win... (without paired board...) and any and every hand has an equal opportunity to do this. So it turns out that hands that have the best drawing capabilites can have that much more an edge. Suited connectors are the best. The high ones (QK, JT) have a piece of their straight-making possibilites limited (2 aces are out). 9Ts (and 89s) would seem the best then- except that a straight of 9-K (QJK) leaves the door open for the AA to make a higher straight w/ a ten). 78s then turns out to the be the best, as the highest of the suited connectors- which can make 4 distinct straights, the highest being 7-J (910J) which will be unaffected (and unlikely beaten by) the rockets being out.