I'm not the type of person who likes actors because they are "hot", as someone who is educated about acting, it's methods and production values and all that jazz, I am all for ACTING, real acting, not fluffy blehh stuff.
favorites?
Kate Winslet <2345-because of her commitment to a character, the ability she has to play so many different characters and they are all SO beleivable. Like when I'm watching Eternal Sunshine...Clementine is a COMPLETELY different person from say, Rose.
Leo DiCaprio- One of the great male actors of our time, sure he's done some fluffy movies (say...the basketball diaries?) but he is a GREAT performer, a great method actor, and he too, is fully commited to his characters.
Rachel McAdams- There is truth behind all her performances, she's had a "real life" and you can tell she brings her real life expiriences to the set.
Steve Carrell- HILARIOUS. Pure comic genius (minus Evan Almighty

)
others; Jonah Hill, Adrien Grenier, Amanda Bynes, Nicole Kidman, Seth Rogan,John Travolta (GREAT in Hairspray!)
least favorites? Jessica Alba- can't act her way out of a paper bag. All she is is hot.
Keira Knightley-same deal
Jude Law-plays the same "charming guy" in all of his roles
Jon heder-nuff said.
best preformances? Anything by Kate Winslet, but probably my favourite would have to be Clemintine in Eternal Sunshine, she was SO REAL and beleivable, brought me to tears (which is easy to do...but still

)
Nikki Blonsky is AMAZING in Hairspray too, I just her HUGE props, it's her FIRST acting role ever and she blew me away!
worst preformances? Tobey Maguire in SPidey 3.
Jessica Alba in....anything.
Johnny Depp in Charlie & The Chocolate factory. SO annoying and obnoxious. (IMHO> flame away, I know you want to)