I can't imagine Thor with a different Loki than Tom Hiddleston. He gave the charisma to this character, making him one of the most memorable villains of all time. I seriously watched Thor: The Dark World because I knew Loki would be there... But did you know Hiddleston auditioned for the role of Thor?
The fact is, I think is better as Loki... Tumblr would be so much boring without him xD
(Huffington Post | Superhero Movie News)