Hezbollah is on the side of Assad, helped bomb 250 Marines in Beirut, with the Senior Assad's assistance likely, Assad, allied with the Iranians whom helped kill coalition soldiers in Iraq. I have little sympathy for them.
Hezbollah firing missiles into Israel, the list goes on and on.
And Al Qaeda is on the side of Al Nusra, launched the 9/11 attacks and numerous other attacks, the Daesh (ISIS) is responsible for numerous attacks on Western interests and atrocities compared with which the Assads, pere et fils, are simply garden variety tyrants.
The Assads, brutes that they are, protect religious minorities, Christian included, from the murderous enthusiasms of the Sunnis shown in the activities of Al Qaeda and the Daesh, and in anti-Christian pogroms back in Ottoman times. And in that, nasty as they are, they are better than the other likely victors in the armed conflict and almost certainly better than the Sunni (not secular democratic, Sunni theocratic) government that would result that a one man, one vote, once election would install.
McCain, from all evidence I've seen, regards the murder of Orthodox Christians as a feature rather than a bug in American policies that have that result. He was visibly angered at Orthodox Christians testifying against American policy in Syria before a Senate committee, is one of the most vicious anti-Serb voices in the Senate on Balkans policy, and exhibits an almost pathological Russophobia (as if it was Russian-ness, rather than Communism, that was the cause of his torment in the Vietnamese POW camp).