Without any real way to determine DPS any discussion is based purely on gut-feelings, so take everything posted here with a pinch of salt.
Myself, I'm in a 10/10 NiM guild that is rolling with the following dps: vanguard, sentinel, sage, commando, gunslinger. Our tank prefers guarding the sentinel since he's been pulling the most, however recently I've started pulling off him as well when I go full nuke mode. I've yet to see our ranged dpsers pull aggro, but they need to do 30% more threat as opposed to 10% for us melee, so that doesn't really say anything about their dps... not that pulling aggro is any real way of determining dps but there you go.
As far as Infernal Council goes I can't really say since I'm always on one of the 78k hp mob so I always finish first by about 15-20 seconds before the other dps come in, usually the gunslinger.
Aside from these two there's no other way of "comparing" dps, at least as far as I know. As for gear/spec I run 8/8/25 and I currently only need Rakata Headpiece, Chest, Legs and Offhand. Could also use augmented belt and bracer but cba now with 1.2 around the corner. My stats, rounded up and unbuffed are:
1720 aim
420 bonus dmg
715 bonus tech dmg
98% accuracy
26% crit chance
74% surge
My rotation is Hammer shot if I feel like I'm about to drop below 8 ammo > Incendiary round dot > HiB > Stockstrike > Ion Pulse
I don't think Vanguards are quite there at the top of the DPS food chain but this is just my guts telling me so. I've watched streams of gunslingers dpsing in NiM and they seemed to do more dmg then I, tho I suppose we're supposed to make up for it with our mobility. If you're interested in numbers, highest I've crit with HiB was 4.7k (w/o sentinel dmg buff), 3k with ss and 2.5k with Ion Pulse.
On a completely unrelated note I did crit fabricator for 11.5k last night, feelsgoodman.
Anyway, there's no real way of determining who the best dps class is so atm if there's 1 dps spot open and the leader has to choose between a bunch of people, his choice is going to be made based around the player, not the class, at least for now, so enjoy it while it lasts till we get dmg meters in.