Before it was, Powertech, Jug, Sin they were the best at dealing damage in OPS, real dps not paper one on your dummy (you need instant dps, any channeling skill is really bad in OPS) but i didnt played few years.
Now im watching stats on parseio and seems sentinels got in touch finally a dps class does more than guardian as tank but lets see, didnt logged in cos stll downloading client.
Get a toon on fleet and ask people, see what is needed you will figure out very fast.