What we don't like about Assad is that he (like Saddam, Khadafy, and some others....) is not JUST a national leader who in involved in ugly stuff, but is a full tilt murderous thug leading a brutal murderous regime.
Moral relativism it all you want, however you shift or dissect the issue, he is bad in a way that only tin pot murderous dictators are, and it is really bad, so bad that it is good deed, in and of itself, to remove him, even by war.
Having said that.....
The brutal experience of the aftermath of Saddam's removal, even with a decade of boot on the ground nation building and massive spending of blood and treasure, makes it clear, that as bad as these evil thugs are, they are NOT even CLOSE to the worst options, and their removal does NOT let 'good' or even 'ok' people fill the void, in THAT region of the world, in THAT culture, removing such evil only invites 'worse'.
So, yeah, no fan of Assad. If he died in fire, slowly, it would be justice. But the alternatives are worse.