Rey, for one, this isn't technically a discussion about CQ. It's a discussion about tournament regulations, which usually means 1v1, maybe 2v2, both of which are very, very different beasts from CQ. For two, if it's taking you more than 3 hits to kill a tank with ACC Kumos, then you are, in fact, doing it wrong. I have been chunked away 30k at a time, in my tank, by ACC Kumos. And, these aren't people using the OW method, either. They're Archibald LRJs with either dual snipers/dual subs, with back-up Kumos, or they've just got the Kumos, with Mathura or CIWS in the shoulder.
As for ACC Kumos, in general, they are pretty stupid easy to use, if you understand the mechanics, and how to get an optimal hit. Hell, you can swing early, and 'slide' into a late hit, and still manage some good damage. Not to mention that they hit from about 25-30m out. Oh, and also, they have an instant animation cancel, which means that as soon as you swing, you can high boost once, before the blade is even out of the sheath, in the animation, be on your way, and still do your full damage.
Sawarabi legs are also fairly strong, but not necessarily due to their own merits. It's more of a map design problem, than anything. Mobility-wise, Ruiz (Sawarabi-non-Archibald), is almost the same as it was in ACV, and people didn't have any issues with them in that game. Not that I was aware of, anyway. So, why now? Because 75% of the maps in VD are flat, barren, open fields, with stuff scattered about that pretends to be cover. With a single jump, most LRJ builds can completely negate just about any cover in the game. Combine this with the abundance of energy that VD provides, and it allows for infinite pressure. And it's not even pressure that you can out damage-race, because just by boosting about, and going from jumping to landing, you can be virtually impossible to hold a lock on.
Streks aren't really a thing to be concerned about, honestly. Sure, they hurt like Hell, but they're really only an issue when you get crept up on in CQ, which, again, we aren't actually discussing here. If you're going to ban Streks because they're impossible to block out, then you might as well ban all laser rifles, any cannon-type weapon, sniper rifles, melee, most missiles, etc. Streks aren't used in duels for a reason. Not even in ACV, where they were even more popular.
So, Skillbreaker... I'll be honest, it had more people on the roster than I expected. Then again, more than half of them didn't show... That said: Everyone talking about balance, and making a fuss about build diversity... Did they not see the same matches I did? After the first round, where all the newcomers and 'less-than-hardcore' players were eliminated, there were basically two builds: Biped/LRJ with shotgun, pulse gun, 3BR, and shield. And Pseudo Lazyquads. Real diverse... Sure, there were a few 'different' builds here and there, but an overwhelming number of builds used the afore-mentioned.
So, it doesn't matter what you ban. People will always figure out what the strongest strategy is, given the ruleset, and flock to it. Ban Archibalds, everyone steps down to ULG-30. Ban Kumos, everyone brings ACC ULBs. The only way that you're ever going to make something completely balanced and fair, for everyone, leaving it entirely up to piloting skill, is to put everyone in the same exact build, and eliminate diversity completely. And, since I know that the AC community would sooner die off, than give up the ability to 'use their own custom, personal setup' (Let's be real, folks, when you're playing competitively, there really isn't room for originality. You either use meta, or you get your shit pushed in. End of story.), I propose a different look at it:
Instead of having a tournament with a list of bans, spin it another way. Have a themed tournament. Rather than "All blades are banned!" make it "This is a guns only tournament!" Maybe instead of "No LRJs allowed!" make it "Heavyweight brawls. Only AC above xxx weight!"
I'll be honest, even though certain things are very, very strong, in the game, I don't agree with ban lists, be they by part, build, tactics (like the one that everyone loves to hate: AP Stalling), or even by what region of the world you live in. You're never going to make everyone happy. But the least you can do is try to include as many people as you can, by not limiting who, or what playstyles can participate. If it ends up being a slugging match between a bunch of identical builds? Well, I'd say that's actually pretty normal.
But, if you are going to have a ban list, then at least go balls deep with it, and turn it into something with a theme, something fun, more unique than "Everyone's allowed, but leave your sniper rifles at the door."