Christian Bale, Edward Norton, John Cusack, Al Pacino (Frank Slade alone would put him in my list), really like Joaqin Phoenix, i'd always liked Heath Ledger but never more than that until his Joker just blew me away, Anthony Hopkins, Cuba Gooding Jnr, Bruce Willis, I'd have
loved to have seen where Brandon Lee's career went after The Crow, Clint Eastwood, Steve Buscemi, big fan of Kevin Costner (guess i'm the only one?), Johnny Depp, Mr De Niro, Sean Connery (just having the moxie to tell the world you think its okay to slap a woman if she gets out of line when your a major movie star, brave brave man lol - disclaimer...i dont think its okay to hit women but i love that he doesn't care
), Ewan McGregor
I can be pretty influenced by one great performance, if an actor can really move me with a role i could watch over and over again i couldn't much care what other turkey's they've done.
As far as actresses go i'm not too sure, funny people rarely ask you for your favourite actress. I really like everything i've seen Rachael McAdams in, Scarlett Johansson does it for me but that may nothing to do with her acting skill, Thandie Newtons good too.
If i had to say a favourite it'd prob be Christian Bale overall, everything from Empire of the Sun to American Psycho to Dark Knight he can't miss for my particular taste.