Kind of hard to pick for me. I kind of categorize my favorites in 2 ways, actors I like personally and actors who blew me away with a performance.
On a personal level I really like J.K. Simmons, Paul Giamatti and Emma Stone but Simmons also blew me away in Whiplash.
Performance wise Brendan Fraser was incredible in the whale. Jonah hills range kind of blows me away especially considering where he came from. Phillip Seymour Hoffman is always spectacular. He also seemed like an amazing guy.