I'm comparing the BK set to Chaos set, and I'm really curious what loadout people use with the BK set that makes it so much more preferred to the Chaos set from a purely offensive perspective. So while the MSI and shadow/freeze resist is nice, that isn't the focus.
Chaos gives CTR and DB very high, while the BK gives DB max. With the chaos set any level 10 weapon has CTR max, while with the BK set you'll need to get the weapon from medium to max. There are UVs, but getting CTR very high on every single weapon you use just isn't realistic unless you use like 2 weapons at most or are willing to dump hundreds of $ solely into UVs.
If you're primarily using swords and guns (as I assume most people do, and bombs are mainly used for support anyway so DB is much more minor), you can run chaos + swiftstrike + level 10 weapons + DB med trinkets for sword and guns, then you'd have CTR max, DB max, and ASI high.
if you're using BK + swiftstrike + level 10 weapons, you can use a gun and sword CTR med trinket, but you're left with weapons having only CTR very high. You can UV CTR med on each weapon which isn't too rare but still adds a lot to the cost, but that also isn't necessary with chaos and would just make ASI as a second UV so much more expensive. With both you can take advantage of battle sprite perks, but from what I see most people use the health bonus and the perks are minor for both anyway.
This combined with the insane price of a BK set just makes me confused why people seem to say it's so much better if you're trying to minmax an offensive build. They're both good sets and BK is slightly better from a defensive perspective, but when it comes to maxxing out your offense, I don't see how the BK set offers anything that you can't get with the chaos set, which is magnitudes cheaper, especially if you're trying to depend on UVs too.
Black Kat vs Chaos for offense?
It is one of very few ways to increase movement speed, being able to run circles around enemies is an understated bonus that adds to gameplay. Also for people who run solo and run fast that time save getting to the elevator adds up quickly.
The movement speed combined with the invincibility you get when hitted means You can reposition over/thru hazzards harmless, if the invincibility where removed... Waw! that would change a LOT (speedrunners would cry a lot, specially those 3 players that got the sonnambulist totem).
The Bombs situation is not minor, yes cookie cutted build use it for "support", but Bombers use it for play the game (that's a different situation).
Damage Max on everything all the time is not accesible unless thru Black Kat, honestly You dont need damage max specially since You play against 2 families at time... Fire storm citadel has Undead-Fiends (and 3 turrets and maybe a Jelly cube) Do You need damage very high against gremlins on the weapon? No.
You use a Combuster against undead, With chaos You need damage bonus Undead medium UV that is a lot more easy than CTR Very high, yet You don't need UV (You have sword damage medium perk) but You wouldn't have medium damage Fiends on the Blitz-Needle against the troyans, because Vanaduke doesn't get affected by Fiend family multipliers so You wouldn't need it anyway, but how dare You not wanting it.
BUT and HERE is the problem.
YOU wouldn't be Efficient farming Vanaduke! instead of taking 15 minutes You would need like 20! that's Unacceptable, How do You expect to farm enough crowns for the next Promo box? You want the next promo box, because obviously You want the next promo box, You have to want the next promo box otherwise You are not cool! and can't play with the cool guys...
Now this is Social Pressure to conform and comply, we know is bad, yet some players keep "suggesting the best gear" to the 2-1(don't even have a sprite Yet) players. And when called out they merely say "what's wrong? I'm just helping", No they are not, they are dragging others to the same lie they have bought: "Get efficient for the next promo box... repeat after me, Get efficient for the next promo box..."
Now let's ask who is to benefit from You, having to get crowns for the next promo box? and re-sell the thing so You get crowns for UV's... and start again? in an unending cycle of anxiety?
Yes people would Cry-out if "something" where to happen to Black Kat, but lets ask Who and Why? but really Why? is the same kind of player that complains because OCH now is free? is the En-franchised player? is the elitist? or a simple played abused by the entire situation? and what would happen if after Black Kats Chaos were returned to it's Original state, Damage and CTR: MED total, not per piece. Would those same people cry out? Would beginners player notice? since the magic set doesn't have any stats until 5*...
Expanding on the post of mine Vyre linked to:
Black Kat is stronger because of its movespeed and higher damage bonus. Universal DMG+6 is appealing because there are no such UVs, only family bonuses. If you aren't using a weapon that needs the CTR, then the missing CTR doesn't matter. If you do, it can be patched up from other sources like trinkets and UVs (and CTR+6 is often superfluous except when pure bombing because of how unlikely it is for firing charges off CD to be efficient), whereas it is impossible for Chaos to recoup the missing movespeed under similar ideal conditions.
You're correct the grind for it is insane and that it's much cheaper to settle for Chaos. Buy mod calibrator and 3* helm/armor scraps off of other players if you must.
Don't think about Somnambulist Totems, plural, and how they fit into this UV pileup.
You might find this post useful. By and large, the difference seems to be "flexibility." BK makes everything more dependable, where Chaos leverages the benefits of a specific playstyle that has a little extra downtime. I figure it's BK's maneouvrability that makes the big difference for a lot of players in the end.