Well, anyways... Assad has killed hundreds of thousands, declared genocide against his own people, possesses nerve gas and other WMD's and has used them, displaced 9 million, created nearly 4 million refugees, started massacring anyone who stood against his regime, and caused a civil war to erupt in his own military as soldiers refused to slaughter their own civilians. His military has somewhere between 150,000 to 200,000 people, 500 advanced aircraft, S-300 missiles which can take down even some American aircraft, and support from Russia in terms of funds and equipment. The military makes about 3 billion a year or more annually.
ISIS has killed a few thousand people, want to make their own country, largely possesses infantry weapon, with a few dozens stolen armored cars and 2 billion dollars in total assets. There's about 20-30,000 ISIS fighters total, and few advanced forms of technology, such as tanks, aircraft, or the like.
So... Syrian forces are larger, possess more advanced equipment, support from a country and have caused significantly more damage. Nearly two orders of magnitude, or over 100 times more deaths and casualties.
But uh, ISIS is the lesser of two evils. You definitely called that one.