Further testing in the playtest, makes this my tankiest build atm.
Playtest GT - Ritualist, Level 100 (GD 1.2.0.5) - Grim Dawn Build Calculator
For those wondering, The Fluffy Squishy - Pet Conjurer - SR 170 version :3 is technically supposed to be tankier, but since Briarthorns die rather easily now while Reap Spirits are still immortal, we end up with the Ritualist having an easier time surviving.