2009 was, IMO, one of the strongest years in cycling history. Contador was riding like unhuman throughout the season, posting dominant times on Montagne de Lure, Arrate, Verbier and very fast despite freewheeling on Ventoux. Schleck was on amazing form, won Liege in a dominant manner, but he could not even come close in the Tour. I think 2007 and 2009 Contador are absolute prime Contador ( and maybe 2011 Giro, with honourable mention to hypothetical 2014 TDF ). Since I'm talking about 2009, another example would be Cancellara's performances in Worlds.
2010 I think it was Contador's one of weaker years but when he had to respond to Schleck properly they were far ahead of the rest ( Madeleine, Tourmalet ). However he also had awful days, such as Avoriaz ( still mad at Schleck for waiting that day ) and the final ITT. But to me it seemed like power outputs had a general drop that year, especially for Contador, his climbing times were not as good as 2009 imo.