Always enjoyed the Federer versus Nadal rivalry more than rivalries like Nadal/Djokovic or Federer/Djokovic. I think it's because of the timing in some ways because Nadal became a factor when Federer was virtually invincible and Nadal was perhaps the only player who stood some sort of chance to win. There was also because of the difference in styles, with Federer the aggressive attacker generally and Nadal the counterattacker, yet both were very good when the roles were reversed. Nadal versus Djokovic often seems like a war of attrition to me and Federer against peak Djokovic is different because Federer is not top Federer anymore.
I agree. The other one that is of interest to me is the Djokovic vs Murray head to head matches. They are the best two in the world atm and have taken over as the premier duo from these two. Either a Djok vs Murray final at the AO or Fed vs Nadal (unlikely but you never know) would be great from a personal point of view.