I like her voice through most eras in terms of studio recordings.
In terms of lives, 2003-2006 was the best vocally. Even now, her voice isn't 'great'. It's tolerable now, unlike 2007-2010 where it was very difficult to listen to certain songs live. So, she's improved, but she's past her prime vocally I think.
Performance wise, she's getting better though, which I think compensates.
