The two main archetypes we've seen so far are
{20 engorge, 20 bind demon, 1 blood oath, bone break + protector's stone}
vs
{20 engorge, 20 blood oath, 1 bind demon, flame rift + defender's fire}
The former build has about 20% less damage vs immunes and 60% less vs non-immunes with blood boil, but has 60% higher bind demon damage, and a higher HP demon despite being 1 point blood oath by using a unique lancer, and frees up 1 socket for MF or mostly offsetting the -% dr on bone break with a ber.
Otherwise the gear / skills / etc on the builds would be identical: 20 summon tainted, 20 blood boil, 20 demonic mastery, 1 hex siphon, 1 sigil lethargy. With ideal runtime gear of obsession in +3 base, shako, +2/20 crafted ammy, ars baalos, enigma, magefist, 2x soj, arach, resist boots. And max prebuff gear of mang songs, +3 circlet, +3 ammy, +5-6 tome(s), enigma, magefist, 2x soj, arach, wraithstep. And swapping in extra skillers, using bone break for joining game, using flame rift for summoning tainted, either way.
You shouldn't be going 1 point engorge either way. You mostly want blood boil against immunes, and the majority of its damage comes from the physical side + amp damage.
So if you are going with option 1, you start with bone break, swap with flame for tainted summon and then you swap back for the - dr for the damage. On paper option one seems stronger, need to try it out.