To me, Indurain is the perfect champion; calm, calculating and quite humble. He didn't attack a lot because he didn't need to. He built the foundation of his wins in the time trials by outclassing everyone. He had already built up his lead before they hit the mountains, so all he had to do was to sit on the other favourites' wheels and not lose any time to them.
Contador is a very exciting rider to watch. He attacks a lot, but can also be calculating. His personality is astonishing similar to Indurain's, and that's one of the things I really enjoy with him. Despite having similar personalities, they are quite distinctly in their racing styles. I would love to see these two riders in a battle for the Tour win. I think both has a good chance of winning, but it depends on the route.
If one of the classic routes that were used when Indurain one his Tours, like 1994, I think Indurain would have won. He would probably be in yellow after the 64 km time trial, and would then defend it in the mountains. But if it hadn't been a time trial before the mountains, Contador would probably had snatched the jersey in the mountains, and Indurain would have to make up time in the time trial instead of gaining. And Contador riding a time trial in yellow would be extra motivated, and would not lose much to Indurain. He would then gain more time in the next series of mountain stages and win the Tour.
So I think it depends on what stage the time trial would've come in the race. I think Indurain would've won if there was a long and early time trial, while Contador would've won if the first time trial came after the first series of mountain stages.