Parts of western and arab press on the one hand and spokespersons of Syrias insurgents on the other hand try to portray the so called „Southern Front“ as the one major „moderate“ faction fighting to topple the Syrian government. They emphasize that this front line which is the only one to witness relevant successes and territorial gains  hardly hosts any al Qaeda or otherwise sectarian militants.

Interestingly though, whenever major attacks on Syrian army positions is under way, the al Nusra is not far:
„Another Syrian province looks set to fall out of Assad government control soon, with al-Qaeda’s Jabhat al-Nusra sending some 2,000 fighters against Ba’ath City and Khan Arnaba, the last towns they yet control in Quneitra Province.“
http://news.antiwar.com/2014/11/20/al-qaeda-attacks-last-syrian-govt-town-along-israeli-frontier/

But al Nusra, which is considered Syrias al Qaeda branch is not the only radical islamist (Salafi) group fighting for the „Southern Front“:
„Al-Qaeda’s Nusra Front and other Islamist brigades and rebels fighting under the umbrella of the Western-backed Free Syrian Army, who the US and other allies want to arm and train, currently have “the upper hand in the area,” Abu Yahya al-Anari, a militant from the Ahrar al-Sham rebel group, said.“
http://english.al-akhbar.com/content/assad-says-isis-not-out-thin-air-israel-continues-treat-syria-rebels

So far the western mainstream news coverage has successfully covered up the role of Israel, but several reports leaked about Israel shooting down Syrian planes, bombing Syrian bases and military equipment and treating wounded rebels.