Hillary was certainly the strongest campaigner she's ever been between the couple days before New Hampshire 2008 and her concession speech that June. By far.
I also think it's rather compelling to suggest that she would have made better use of the congressional majorities than Obama did in the first two years of that term. On the flipside, many Obama primary voters probably would have acted just as rotten as Sanders voters did had she actually won the nomination, so that would have been quite challenging.
But yes, I'll say it over and over: Hillary's time was 2009-2017. Obama would have fared well as a successor in this environment, and in fact would have been a better president with more years under his belt.
This her best time was 2008.
Imagine a grizzled and seasoned two term VP Obama running in 2016 to continue Hillary's legacy? Obama would have been very tough to beat in those circumstances.
Obama would have lost his popularity among the liberal base if he was her vp .
Biden hasn't lost popularity among the D base for being Obama's VP. Obama would be untainted and charismatic enough to move left in 2016 and appear genuine. After all, what hurt Hillary with the base wasn't what she did in the Obama administration so much, but her record in the neoliberal 90s.
Whether Clinton would have won re-election in 2012 is the more interesting question, as Obama that year ran the best campaign in Presidential history. But on the other hand, perhaps Clinton wouldn't have suffered quite as big a landslide against her in the 2010 midterms. Who knows.