i think dicaprio is at or near the top for this generation... i love the character actors who dont get much love or starring roles like buscemi and brolin, keitel, platt, oldman (i like him best in his character villain roles although he does star in a bunch of movies), tarturro.... denzel is always solid but doesn't pick enough good roles for all the bad movies he's made tolerable... his last great role was man on fire imo although he was really good in AG.... other good actors of this generation:
gosling, damon, jon hamm (dude has range), firth, DDL and bale are excellent method actors, pitt, norton, spacey, malkovich, ledger, clive owen, depp, ralph fiennes, joaquin phoenix
im sure i left out a bunch but this is off the top and dudes that are still major players and command attention... i feel like the DeNiro's and pacino's of the biz have lost a lot of their flare and can no longer lead a classic movie although i loved pacino as jack kevorkian