Not a defined decade, but if I had to pinpoint a favourite 10 year span, it would be from 2004-2014ish give or take.
The talent on display across the league was ridiculous - and getting home from school to watch any WC ESPN-televised game - as the time-zone aligned perfectly - was such a treat (because the WC was so stacked back then). There were so many good teams out of that WC during that late 00 period - Suns, Spurs, Mavs, Utah, Houston, Denver, Grizzlies and later the Lakers. Some incredible battles.
League probably peaked in 2007 in my opinion.
The fact that I was in HS for most of those years helped as well - the game always seemed so pure and exciting as a teen; now as an adult, the commercialization (+ all the things that you were too naïve to notice as a teen) are more conspicuous.