Really depends on how much time you spend out of stealth and your build. I spend a lot of time out of stealth and use a Bloodtheft enchant and it works great when I'm getting ganked but not so much in a 1v1 match (be it bosses or PvP) as the amount you heal is dependent on how many enemies are around to steal from.…
Gloaming cut is something that really can't be compared to the others. It's more of a situational move rather than a go-to offense. I usually chip the enemy down with DF or SF and then start knocking big chunks off of the HP with gloaming as it gets stronger against damaged foes.