I think what makes it intriguing is having 2 riders that are dominant, to where they go a mano v mano battle, where they both try to destroy the other. Then something like the 19 Giro, where a upstart takes advantage of the feud of 2 riders and then that puts the 2 riders forcing to be more aggressive.
Now as far as the topic about Contador's impressive levels (I am using this term literally) I dont necessarily rank his 2009 Tour as number 1, because his competition was not nearly as strong as some of the other grand tours. In 09 you had a almost 40 Lance, Bradly Wiggins when he first was transforming into a stage racer. Also in the Top 10 if I recall right was Le Mevel, Casar, Vande Velde had his best Tour finish. Plus the route wasn't very exciting as the previous years. I only thing that exhibited how strong his level that day was his TT win over Cancellara.
To me, his most impressive Level was the 11 Giro. HE was so far ahead of everyone, he was gifting stages (Which helped win the 12 Vuelta with the gift to Tiralongo.)
I think his level at the 07 Tour was most impressive of the 3 TDFs win, because he was able to Stop and Start so many times, it just Rasmussen was on the same climbing level as him.
The Giro 2015 is so hard to judge because he crashed in it twice and didn't win a stage if I recall right, but he did have 2 fight off the 2 headed Astana monster. I would say his level was better in the 2012 Vuelta. Its played off of the De Fuente victory that he was that good, but Purito was flying that Vuelta, and as we all know, Purito and Valverde always find their best form for the GT at the Vuelta.
So I would right now go with my list being
- Giro 2011
- Tour 2007
- Tour 2009
- Tour 2010
- Vuelta 2014
- Vuelta 2012
- Giro 2015
- Vuelta 2008
- Giro 2008