If somebody will disagree with 2000-2009, it won't be me.
That decade wins it handily. It was fun to see an unknown girl living on a relatively obscure island in the Mediterranean Sea win over the hearts of France with her talent, beauty and charm. That decade was also the time when the Internet started maturing as a social medium, with the creation of MySpace and YouTube and others, allowing Alizee's popularity to spread across the world. Even thought there was the disappointment of the breakup with Mylene, it overall was a great decade to be an Alizee fan.
However, I do want to give special mention to the 2010s. Her Les Enfoires appearances were awesome. Then there was the DALS victory. For fans just interested in Alizee's music career, the decade was pretty much a fail. For those like us in the forum who like to follow all things Alizee related, it was a decade where we saw plenty of victories in her life, both personally and professionally.