The best hand to crack aces is 76/78/89 suited, they have approx 23% or close to that to beat AA since they have the odds to catch a flush OBV there suited, and they can hit both sides of a straight higher or lower. Now how you are getting beat with your AA is because mainly of your bad betting. If its just me in early position i throw a raise of usually 4x bb, and usually i'll get 2 callers max, and no matter what hits that flop im betting 75% of the pot to show strength. Once you get a caller though you gotta think wtf they got and they also have you out positioned. If theres a flush draw there or straight draw there and nothing hits the turn like a low card i would immediately then bet 80% of the pot to get em out. I think you might not be aggressive enough. You seem like you want to put in a small raise and keep people in because you think AA is uncrackable. News flash as you've seen they are. Aggressive poker is winning poker. If your not aggressive enough you will constantly keep losing.
If someone hits a set off of the flop or two pair which is possible, then you are just unlucky. Even if you hit your set on the flop unless its like 3 9 A where theres no possible chance for a flush or straight coming on that turn then i would come in on the slow play.
Perfect example yesterday was playing in the 20$ turbo jackpot SNG yesterday on Titan
and this guy decided to raise x3 the BB and i had A4 suited and 2 others calls so i decides to see what all the fuss was about and the flop hit QKA, Im on the button(best position), and he checks it and as so everyone else around because i hate someone raising and checking on a flop because it resembles a lot of strength usually. The turn came out a 10, he immediately pushed all in. Everyone folded except the SB who called because obv he has the J, it was a tale of QQ vs QJ and since the flop was QKA10, QJ is beating the set with its straight, and rver came a blank so the QJ won. HAd the QQ came out with a nice strong bet on the flop he could have avoided this, but he was trying to be fansy and wasnt aggressive enough on that flop. Try to stay away from stuff like this. Its not good for ya
To the End!