I realize that it may be too late to help, but the Zenith is the real star of those three. Infinite punchthrough on the altfire mode.
All of those are solid performers. The Tigris is the shotgun you pull out when you want to pick up a whole 100000-square-foot brick mansion and bash something over the head with it. Sybaris does well for marksmen; very nice headshot potential. Soma is the king of spray-and-pray with its absurd crit chance and rate of fire. Quartakk is the least good of the option you've listed but still good in burst fire mode; you're usually going to be better off with burst as the automatic has a pretty low rate of fire.