That's difficult to choose.
It was really special to see Roger playing live for the first time (Hamburg 2007 against Juan Monaco), I also enjoyed his match against Roddick in Basel 2010 and then the final of the same tournament against Djokovic.
It was great to see Roger winning a title and celebrating it afterwards with other fans
It was special to be at the Match for Africa in 2010 and to see Roger and Rafa on the same court even though it was just an exho.
I also enjoyed the Rotterdam 2012 final between Roger and DelPo and loved it to see Roger winning that tournament
To name a Non-Roger-match which I especially liked:
The final in Halle in 2009 between Tommy Haas and Novak - with Tommy winning