Collision Course will always be a highlight of LP's career in my opinion. My favorites are Jigga What/Faint, POA/99/OSC, and Numb/Encore.
Have actually had it on in my car for the last 2 weeks. I'm a big fan of the collaboration. My favourites would be all of them except Izzo/In The End and Big Pimpin'/Papercut. Really didn't do Papercut or In The End justice.