It's between 2 different shots for me...
November last year (I had only been playing a couple months) I went to AZ and played Vista Del Camino and aced hole 16 in the second longest position (272 ft). For those that don't know the regular layout, it's the same hole that Barry Schultz aced at the memorial last year. The awesome thing is that it was a day or two before my birthday. Also, it was the day that UO beat ASU (football) which was cool since I was in AZ.
My other favorite shot is my 7th ace on hole 7 at Ewing Young. It was the first time I had ever
played the hole and before I threw my shot I had the crazy feeling that I was going to get an ace.