1) Federer 2005 was the best I have seen (unforgettable Agassi match). But I believe the conditions back then used to be quite a bit faster, so it's hard to compare.
2) The Safin match against Pete was very impressive, yet for me it's more about classic vs. modern tennis.
3) Gotta respect Del Potro's monster match in 2009, he was on his way out when thunder struck. Awesome stuff.
The rest is more about Djokovic and Nadal. I liked Nole best in 2011 when he attacked more, but his best stuff is still at AO. Nadal was really impressive in 2013, serving better and adapting his tactics.
The worst was definitely Murray's 2012 win, even though I was happy for him to break through. What a weird match!