CD,
I really hope Rafa does it, because I think he's had a much harder road to glory.
Hi TT, I don't necessarily think so. Mainly because, as I see it, Nadal only had to deal one opponent at a time. For example, from 2005 to 2010 it was Federer and Federer's best years were from 2003 to 2007 in the sense of peak time, so by the time Nadal finally started exploring outside clay, Federer already had his best years behind him. In those years, he pretty much dominated all surfaces other than clay. It's to only Federer's credit that he continued to play very well even after 2008 and stayed very, very consistent.
And Nole didn't peak until 2011 and Murray until 2012. In those years, Nadal only had one true rival and that was Nole. Murray had always been a mental midget - reason why he had to go and get Lendl so that he could finally take that quantum leap and these two haven't met since then. For example, in 2012 Nadal didn't play USO. In 2013, Nadal didn't play AO and Murray didn't play FO and while Nadal went out quite early at Wimbledon, Murray too followed suit at USO, so Nadal never had to play against Murray. He was still left with to deal with one rival only. So while his best years are definitely 2008, 2010 and 2013, he didn't necessarily face more competition than Federer.
It's actually Nole and Murray who have much tougher roads than both Federer and Nadal as they had to face both Nadal and Federer not to mention each other since 2008.