OK, since I'm here

Andy in 2009 was still finding his feet really and was up against a super motivated and no doubt very angry Contador = no contest. 2010, avoiding all the usual he* should have waited nonsense (*insert as appropriate Contador/Schleck) was a pretty much even affair =. 2011 TDF was a blow out for AC for many reasons. It totally affected Schleck's ride and no doubt he messed up badly bacause of that (his v v bad no excuse).
No comparison but I doubt anyone other than a total Schleck fanboy would argue against Contador IF he had brought his Giro form. So on balance will give it to AC.
We won't see how they now match up until 2013. Schleck should stilll be on the up. In theory so could AC. I see 2013 as the first true battle between the two. A more mature Schleck nearing or at his peak against a Contador still at his peak and most likely still seething. Let's hope for a TDF route worthy of this potential mega showdown