Assad, mostly just because he doesnt persecute ethnic minorities which helps in calming things down -> less refugees.
The problem with Syrian opposition is that they're a) Sunni radicals, b) Kurd ethnonationalists, c) progressive retards.
The problem with group A is the terrorism and genocide. Less well known is the Kurd persecution of Christians and other ethnicities. Trump made the right call pulling out, because it forced the more nationalist Kurds to make peace with Assad. Had the US not done this the Kurds would felt confident enough to continue the civil war, and execute some civilians probably.
Problem with group C is that they were taken for a ride by Sunni radicals. If Syria does one day become a democracy, it would differ very little from the foretaste of the Islamic caliphate we already had.
If anybody but Assad ends up in power, Syria is fucked. Lets hope the western world learned its' lesson with Saddam and stops forcing democracy onto already unstable nations.