Sniper / Gunslinger
Operative / Scoundrel
Marauder / Sentinel
Feel confident in that top 3 order, everything else is pretty even as far as DPS specs go.
Op/Sco has the higher upfront damage but sniper specs have long term consistency and less CD's or positioning requirements.
I think it's a safe bet to say Ops and Scoundrels aren't the highest at PvE b/c they can only use their big damage attack a few times in a boss fight. After that their sustained damage drops way down.
My list would be (also including the republic counterparts):
- BH Mercs
These classes all have good sustained damage that can burst pretty well at times. No one will know anything of course until we get combat logs that everyone can see. Even if we get personal logs it will be too easy to fabricate numbers.