Here is the list of people who've gone top 10 in both the Giro and Tour in the last seven years:
Denis Menchov, 2008
That hardly bodes well for Evans or Basso or Vino (especially Vino since he'll not be his team leader). I think people underestimate just how much that Giro took out of people. Bear in mind that Evans has had to be in form through April too, and was visibly running out of gas at the end of the Giro. He only just managed the top 5 at the Giro, and now you think he's going to podium at the Tour, with even less support than he had before, fatigued after the Giro, and with a tougher set of opposition? His riding will be pure and ballsy, but I will be absolutely shocked senseless if Evans podiums. Even acf says he'd be better off losing time and going for the KOM or stage wins, and acf believes Evans could win every race on the planet and would if it weren't for conspiracies! Also, Liquigas targeted the Giro, and many of their best helpers were there. Will the likes of Szmyd be as good in consecutive GTs?
I also think that the people voting for the riders who've just blown our minds and their gaskets in the Giro are underestimating the benefits of being fresh, and recent race training; the riders who rode the Giro will need most of the month off to recuperate for Le Tour, while the riders peaking for the Tour without doing the Giro can build up through June. Menchov is always going to be worth mentioning; he has 3 Grand Tour wins, 3 times as many as Vino, 1 and a half times as many as Basso and infinity times as many as Evans. I'm not saying for a second that he's a better rider than them, but he knows how to deal with the pressure and the Tour is all he has left to achieve. He also has a strong team behind him. Samuel Sánchez is also a good option; he beat Evans at the Vuelta last year, and the parcours could aid him. Working against him are that two of Euskaltel's best riders - Igor Antón and Beñat Intxausti - are being kept for the Vuelta, and that he will be one of the most vulnerable GC men on the cobbles since he doesn't really have anybody to guide him.
Finally, the Tour always throws up a surprise or two; Wiggins in 2009, Kohl and Vande Velde in 2008, Contador and Soler in 2007. I'm sure there will be somebody up there we wouldn't expect. Soler is a possibility; he has looked much more like the Soler of 2007 this year, and Caisse d'Epargne have a very strong support team, they just need somebody like Soler, Sánchez or Cobo to step up and lead them. Rodríguez is another - he's got two GT top 10s riding as a support rider, and the parcours limits his losses by including few TT kilometres.