You actually have some pretty decent taste, excluding Nickleback. I mean, I know it's catchy, but c'mon their music objectively sucks.

Anyway, artists I like... I'll stick to my tastes as of the past couple weeks.

[hider=Metal and Rock]
Halestorm - probably my favourite band right now
QUEEN - I WILL LOVE THEM FOREVER AND EVER. Bonus: They originally formed at my university. :D
Muse
In This Moment
Stone Sour
Slipknot
Bring Me the Horizon
Linkin Park, Breaking Benjamin, and Three Days Grace (for some reason I always conflate these three mentally)
Alterbridge
Disturbed/Device (same lead singer and similar styles so I'm sticking them together)
Marilyn Manson
Rise Against
The Darkness
[/hider]

[hider=Others]
Eminem and Hopsin - only rap I really listen to.
Damien Rice
Deadmau5
Amy Winehouse - what a fucking goddess. Tragic what happened to her.
Red Hot Chilli Peppers (one of the few bands for whom I can't think of a single bad song)
Been listening to some jazz/swing - Ella Fitzgerald, Julie London, Duke Ellington, Peggy Lee
Alanis Morissette - just started getting into her
Michael Buble - the man, the legend.
Justin Timberlake (shutup he's got some good songs okay?)[/hider]

Problem for me is that I tend to listen to playlists composed of a bunch of random songs than to artists/albums, so pinpointing favourite artists is hard. I mean, I might love those three songs by X band on Y playlist but I don't know any more of their discography and so can't really say I like them as a band.