I really liked David Tennant, and I didn't dislike Matt Smith.
But I loved the intensity that Christopher Eccleston brought to it, and I'm geeking out pretty hard right now because I know that Peter Capaldi is more than capable of bringing that back.
David Tennant (and Matt Smith) could easily make you believe that The Doctor had seen some terrible things over the centuries. But Eccleston, and I'm betting Capaldi as well, can make you believe that The Doctor was the terrible thing.