I'm going to be a stinker and not make a list, but I'd like to say that I consider it an amazing musical year for me when I discover at least one new band whose entire catalogue I sincerely enjoy.  To that end, I completely agree that tastes can and should change because there's always room for more love in our musical worlds! ( I've made mountains of room in my heart for The Wombats and WALK THE MOON this year). 

...those first five are pretty much set in stone.  The only change the past 20 years is that somewhere along the way, U2 eclipsed Zep for me.  The next five are always in flux; 2 years ago, Sarah would've been #6 and Steely Dan would've been #7, but my attentions have been elsewhere over the last 18 months.