What about the situation in Mosul, Iraq where, according to media reports, US airstrikes have killed hundreds of civilians in recent weeks? This could be war-crime.

Anyway, as far as Syria is concerned, every sane person would rather have Assad than ISIS. 

Not mentioned by the author, but in fact the so-called rebels consist of tens of thousands of extremist Islamists from all over the world. They invaded Syria to establish an extremist Islamist state or caliphate. Twelve thousand from Tunisia (the single largest contingent of Islamists in Syria), thousands from every other Arab country, thousands from Europe, Asia and North America, including hundreds from Canada, according to CSIS.

If Assad had been deposed then ISIS would own Damascus. That would mean a bloodbath far worse than anything we've seen so far in Syria. It would also mean the extermination of every religious minority, including Christians (who, along with every other religious minority, overwhelmingly support Assad).