Lets face it, no matter how awesome instrumental music can be, and the same goes for more progressive fare, there is literally nothing that can beat a huge sing-along chorus that imprints itself on your brain.

So, what are your favourites? There are so many that I love that its almost impossible to think of any real standouts, but out of recent released, probably What Death Leaves Behind by Los Campesinos!
http://www.youtube.com/watch?v=JXfC9N-zm04

In terms of all time though, I think some of my favourites include Always:Your Way by My Vitriol (http://www.youtube.com/watch?v=egoef0mWIeo), Tonight Tonight by Smashing Pumpkins (http://www.youtube.com/watch?v=NOG3eus4ZSo), and Sweetness by Jimmy Eat World (http://www.youtube.com/watch?v=ROatPGGMvXg).
Also, why don't really like the rest of the song or the singers style, or even particularly the lyrics, this has an absolute belter of a chorus: http://www.youtube.com/watch?v=HKoqoZfJysE