I'll share my builds, in order of most to least favorite.
All rounder bruiser

No frills get-in-there-and-hit-things build. I've been using the Arbites shock maul and the mk8 executioner shotgun, though probably any ranged weapon besides autoguns work fine. I don't even think the executioner shotgun is better than the bolter but it's not as unwieldy and can still snipe specials. I just like it. I think the biggest weakness the Arbites has is gunners so I'm using two gunner resistance perks on my trinkets. He doesn't have a ton of toughness DR and can get shredded easily if caught in the open. Could probably drop the charge distance node for another damage node somewhere but whatever.
Castigator's stance shooty bang bang

I personally enjoy castigator's stance as a ranged augment as my melee playstyle has always utilized lots of sprinting and sliding (I know you can dodge-slide in castigator's stance). Good with the mk3 executioner shotgun, shotpistol + shield, or bolter. I don't think this build is that good in maelstroms or havoc as there are too many armored enemies but it's fine otherwise. There's probably a way to incorporate the dog into it and make it a boss killer but bosses aren't enough of a threat outside of 3-vegs to make that appetizing.
Dog explosion

The only way the dog works for me personally. My new criteria for a dog build is "can the dog plus the explosion output approximately the same damage as lone wolf plus impact nades over the course of a map?" If it can, than it's usable. It'll probably still be ok even if the interaction between puncture and remote detonation gets fixed but right now, that's what lets the build clear out packs of elites effortlessly. I tried using a mod (
Less Annoying Arbites) to help distinguish and control the dog better but I think it messed with the dog's AI, resulting in a a propensity to
not pounce or roam and also at times broke entirely with the dog sitting at the start of the level until entering an airlock.
"Support"

Not particularly fun. Doesn't have the offense and isn't as survivable as the break the line/forceful build. The cd on nuncio aquila is so damn long that it practically forces you to take execution order with the cd node to have usable uptime. Nothing else to say. I used this to get the nuncio aquila penances and then washed my hands of it. Theoretically there is a bunch of "support" stuff tucked away in the Arbites kit but a lot of it doesn't jive well with the rest of it.
Some thoughts on certain choice nodes, both the good and the underwhelming:
Up Close, Force of Will, Concussive, and Suppression Protocols: these four nodes I think belong in every build. Up Close and Force of Will give the class its toughness regen which it needs lots of, Concussive enables most of its damage output and also makes it not useless in havoc, and Suppression Protocols is a cheap one point DR node next to a node you're going to be taking regardless.
Zealous Dedication and Soulguilt Scan: massive damage increase. The shotpistol and executioner shotguns have higher than normal base crit chances. Slap scattershot on the mk3 shotgun and you're almost guaranteed to crit. Most melee weapons have access to aide horizontal swing patterns for easy horde clear.
Strike Down: I used this initially but swapped it for The Emperor's Fist. It's not as good as a tier 4 blessing. Virtually every melee weapon has an anti armor option that's better than this mode and most do decent armor damage anyway.
No Lenience: 10% rending is crap. This should be like 25%. It's amazing how stingy the game is with rending.
Rebreather: incredibly niche but probably quite good on certain havoc maps. Having a node that you take on specific maps is cook, almost like having an extra piece of gear in tow.
True Grit: in theory this makes you super hard to kill but the class is already blessed with high defense through a powerful offense. Outside of mistakenly tanking an overhead or a sniper shot, death tends to come through lots of small chip damage instead of big oneshots. I wish this node was something else or was incorporated into a keystone. There were a couple talents that were this exact effect (with different numbers) in VT2's pre 2.0 talent trees (I think on zealot and slayer).
Terminus Warrant and the rest of its keystone nodes: I don't think this is the worst keystone in the game but it's certainly awkward and underwhelming. I figure that's because there isn't really any feedback besides attack speed and reload speed, unlike Weapons Specialist which has a mobility component. This keystone should probably be reworked and soon. The whole balancing stacks act is more maintenance than playing grenadier vet.
Judicial Force: I see what they're trying to do with this node (use it with Arbites Vigilant) but the issue is that anyone using Forceful is almost assuredly also using Break the Line which already does a stun so you take this node to get a stun when reaching 10 stacks? Ok who cares.
Rapid Movement: none of the effects are worth the node. 5% sprint speed is nothing and 5% stamina on kill with an internal cd is also worthless. Just use stamina regen.
Street Smarts: another almost must take node. Psyker has the same node, albeit slightly better, but Arbites weapons are slightly less agile.
What I really like about the tree is that almost all the tiny nodes that plague the other trees have mostly been done away with and the ones that remain have a greater magnitude than the others. There aren't really any tax nodes besides maybe No Escape when trying to go for Razor-Jaw Augment. I also like how there aren't any exclusive nodes on the keystones or abilities.