Uummmm...gosh..that's really a difficult q..I like so many and here's a top few off my head in no order..
Gary Oldman - genius and he can really play so many versatile roles
Al Pacino - any man who can pull of a great cop/mob movie and do Shakespeare?
Anthony Hopkins - Shakespeare roles and Hannibal? Done
Mel Gibson - personal BS aside, I've always loved him as an actor!
Liam Neeson - sexy Irish accent and interesting characters in some really good movies!
Samuel L. Jackson - need I say more?
Ken Watanabe - amazeballs!!
I also adore Johnny Depp, but since Fear and Loathing in Las Vegas, I see his "Hunter S. Thompson" quirks come out in every role he does now...so I don't feel he's that diverse any more...so he's not my fave in the skills department, but he is talented and drool worthy lol.