Nadal's is better - think about it... everyone wrote him off after getting destroyed at WTF '09 and beaten by Murray at this year's AO. No one thought he had chance chance in hell in winning a slam again never mind completing the GS set. But won against all odds to claim his first USO to complete win all 4 slams at 24 years of age. He may not have won this year's WTF to finish the year on a high but there was more pressure for Rafa to deliver whereas Roger was expected to win everything back in '07.
Don't you think that if people expected Roger to win back in ´07 that was also called pressure? A lot of it.