Based purely on recent work? I'll mention the films that I enjoyed their performances in:
Michael Fassbender (Hunger, Inglourious Basterds, Fish Tank)
Robert Downey Jr. (Zodiac, Tropic Thunder, Sherlock Holmes, Iron Man 1 + 2)
Jake Gyllenhaal (Donnie Darko, Brokeback Mountain, Brothers)
Casey Affleck (Gone Baby Gone, The Killer Inside Me)
Leonardo Di Caprio (The Departed, Shutter Island)
Honourable mention goes to Christian Bale, I nearly always enjoy his performances. Even in the much maligned Public Enemies and Terminator Salvation I think he did the best he could with what he had to work with.