Sniper / Gunslinger
Operative / Scoundrel
Marauder / Sentinel
Sniper/Gunslinger I think has the highest burst DPS, but you will blow all CDs to do so and get low on resources.
Ops/Scounfrel has high damage when there burst from stealth/positional moves are used.
Marauder got good damage, and is the best in terms of long term DPS due to resource mechanics (longer fight = more resource to spend).
Others in DPS specs do nice damage as well though from what I seen.
TBH theres not a lot in it between the classes in DPS specs between the 8 classes (I think its something like 20% dps between them).