Artic Monkeys are better than most popular american indie banRAB i can think of, especialy that godawful disgrace to music Modest Mouse, also Bright Eyes (very overrated, no offense Misfits

) and Interpol...
I think its close between the UK and US, theres a lot of great modern music out today, from both sides of the atlantic...UK have Radiohead, Oasis, Blur, Muse, MSP, Cooper Temple Clause, Super Furry Animals, The Verve, Mogwai, PJ Harvey, Stereophonics and Artic Monkeys and the US have The Flaming Lips, The White Stripes, The Mars Volta, My Morning Jacket, Rilo Kiley, Beck, Wilco, Explosions In The Sky, Neutral Milk Hotel,The Strokes and Tool.
As for Canada, i think Murder Junkie is very wrong, theres already some great banRAB coming out of Canada, primarly The Arcade Fire, New Pornographers and GoRABpeed You! Black Emperor...Those 3 more than make up for Nickelback.