I know for a fact that I could never say a favourite band or even a favourite list of bands because ten seconds later I'd rush back to change it... Then ten more seconds later... And then ten more seconds later... See the pattern?
I'll put a few bands though just because I saw them recently;
Avenged Sevenfold-----\
Bullet for my Valentine--> E-P-I-C Live!
Atreyu--------------------/
Otherwise I'll just comment on everyone else's bands:
Elliot Minor -- Haven't heard.
Nickleback -- Utter crap.
Paramore -- Haven't heard much, not so good.
Blink 182 -- Meh,
few[/i] good songs.
Rage Against the Machines -- MACHINE - NOT PLURAL! But yeah, awesome band, some songs are way too repetitive though.
Linkin Park -- Again; meh,
few[/i] good songs.
Madina Lake -- Haven't heard.
Green Day -- Several good songs.
Fallout Boy -- Shit.
Good Charlotte -- Used to be good, now shit.
Rise Against -- Quasi-good.
Slipknot -- Fecking awesome.
Dragonforce -- Sweet.
Metallica -- <insert string of profanities> awesome!!!!
Simple Plan -- You're not serious... They get a big: C R A P.
Lost Prophets -- Familiar, but I can't bring any songs to mind.
The Who -- See my response to Metallica.
Van Halen -- See response to The Who.
Journey -- Haven't heard.
AC/DC -- See my response to Van Halen.
Foreigner -- Haven't heard much, good though.
The Rolling Stones -- Brilliant, but many songs are pretty meh.
Led Zeppelin -- See my response to AC/DC.
Aerosmith -- Pretty damn good.
Nightwish -- Only heard a few songs, good but I don't like the vocals.
Arch Enemy -- Few songs I've heard are pretty good.
Lordi -- Haven't heard.
KISS -- See my response to Led Zeppelin.
Heart -- Damn fine band.
Lacuna Coil -- Cool.
The Rolling Stones -- See my response to The Rolling Stones
Pink Floyd -- Average.
Opeth -- OK from what I've heard.
Evanescence -- Meh.