Gogoplata is top of the list of course, if you're waaay flexible and learn how to bait people into setting themselves up for it it becomes much easier to pull off, but it's still at best35-40% sucess rate to pull of a nice tight choke.
In no gi grappling or MMA Barbo and D'arce chokes are great, but any head and arm set-up I'm rather fond of.
Also kneebars, sit-thru knee bar being my personal favorite and one you don't see to often. To be honest I think it's easiest to hit hit them off an Ankle pick from a head tie-up. You just control the leg, step in, and backspin and fall through into a kneebar. (just remember to tombstone your arms and flex your hips