Depends on the job.
You engaging hordes of adds? The Hereafter, hands down. It will incapacitate entire crowds of enemies (including majors) in mere seconds.
However, its poorly suited to shoveling out heavy damage to ultra level enemies. If you're up against a strike or raid boss, use the Spindle.
While the Hereafter specializes in the support side of sniper support, the Spindle is all about massive damage against [i]unshielded[/i] enemies -There isn't a weapon in the game that can currently match it in raw, sustained DPS.
Anyone who didn't say Black Spindle probably doesn't have it. Hereafter isn't worth the exotic slot, especially seeing as 1000 Yard and Eirene both have much better impact.
So want that spindle. Tried to get it for HOURS last week and could clear out the mobs at the end. Will try again next time now that I have the simulant. Have enough experience to do it, but need to dps the boss faster.
I use spindle for all bosses on the raid except for oryx. I'll switch to the hereafter because of the higher rate of fire and extra bullet since oryx doesn't have a critical hit spot. Also since I don't have touch of malice yet.
Not really comparable other than they are both snipers. As with everything else in the game, these are both situational.
In terms of DPS, Spindle wins all day.
Other than that I enjoy using the Hereafter very much. The blinding perk procs often enough in pve and pvp that I can justify it taking up the exotic slot.
I suck at sniping, but decided -blam!- it I'd use the hereafter.
I don't give a shit about what anyone says. This guns fun to use and is taking me away from shotguns.