I tried the Bone Spear set earlier today. Play style seems fluid enough. Has problems right at the beginning of a rift because no corpse = no enhance bone spear, so your damage is shit. The set will definitely run into problems on higher GR bosses. The stacks cap at 30 and you can definitely cast that many on some longer boss fights. I hope they change the set from relying on corpses.
It is quite fun, however, to use Devour and the aura rune to see corpse lances being flung everywhere. Too bad the damage is shit. Maybe they should add corpse lance to the 6P bonus. It will definitely help with bone spear's poor ability to "spread" damage. Even with the teeth and shatter(best rune imo), your AE is still quite limited.
I haven't tried the bone armor set yet. Don't have high hopes for it since the damage bonus doesn't look that good and the tornado itself looks kinda small. About the same size as cloud of bats.
The pet set is easily the strongest. I'd be really surprised if the bone armor set comes close to it. For a pet set, it's not nearly as boring and frustrating as a WD's zuni or garg builds. You bypass a lot of the stupid pet AI by only using skeletons and mages with the contamination rune. So you can either tell the skeletons where to attack, or you're actively placing mages. The best part is no need for builders! Seriously, blizzard, drop this shit, nobody likes it. Through 99% of the rift, you get your essence back via devour and reaper wraps. And collecting globes is easy with the blood sucker rune on siphon.
Pro tip: siphon seems to tick immediately but the animation can be canceled much earlier than other builders. So even though it's only 15 essence, you can tap tap tap it much more over time. Works great for tossing one in between a couple mages to pick up any globes nearby.
The set might run into issues when rift boss hp eclipses 50k weapon damage(land of the dead), so you'll have to actually rely on siphon to get essence.
One last gripe: please please please do away with "long" cooldowns. I don't understand the point of 2m cooldowns. The longest cooldowns should refresh in between elite packs.