Believe it or not, Messi's 2nd against Bayern is definitely in the top 5 for me. It was an amazingly aesthetically pleasing goal, that was vital and clutch as fuck, against Neuer and Boateng, two of the best at their respective positions.
My top 5:
5. Maradona goal vs Getafe 2007, really began his legend.
4. Away goal vs Zaragoza, 2009. Shows everything that's great about him, out muscling the man on the ball with defensive contribution even though dude is like twice his size and the fake inside the box is what did it for me. Great goal.
3. Home goal vs Milan, 2012. Amazing goal, Abbiati could literally do nothing but watch the ball curl inside.
2. Home goal vs Bayern, 2015. First time I've ever witnessed a murder on live television. RIP Boateng lol.
1. Away goal vs Madrid, 2011. Like Flavia said, nothing better than watching our crown jewel, bred and created at La Masia, destroying a billion dollar team. Ronaldo's reaction to that goal is priceless too lol.
He has so many highlight reel goals though, it really is just a matter of preference. His FK against Atletico in 2013 was amazing too.