Omnipotence, given it can literally achieve anything you set your mind to. Prior to Omnipotence's introduction, my answer would've been COAT for the same reason. Omnipotence is just COAT on crack essentially.
The Sharingan.
I mean, the possibilities are endless with the Sharingan. Genjutsu would make life a whole lot easier for obvious reasons. Being able to perfectly analyze, understand, memorize, and replicate any physical action is insane. You can just become a martial arts grandmaster by watching a bunch of UFC fights or something.
IF I had a way around the blindness, I guess my Mangekyo Sharingan of choice would be Obito's.
Teleportation is insane in this economy given how much money you'd save on transportation. Being essentially invulnerable to physical damage is OP too.
The BFR is great in combat, but also an insane business opportunity
The Kamui dimension being such a convenient storage unit has a TON of potential. You can become quite an insane shipping enterprise singlehandedly.
And the Susano'o is just a cool ass bonus.
My answer to both of these is Shadow Clones. Just insanely convenient and useful whether we're talking about In-verse or IRL.
Great in combat for obvious reasons. Their ability to distract and overwhelm with numbers is amazing.
But their general usage is what interests me. The fact that they allow you to delegate tasks and work WHILE still gaining experience and knowledge is insane. Like, you can finish reading a book in a fraction of the time, but still gain the same amount of knowledge.
You can have the clones do the more unpleasant things you don't feel like doing like cleaning, doing the dishes, etc. Just so goddamn useful.
It's not a "hax" per se, but my favorite jutsu is Kirin.
My favorite hax abilities tho are prolly:
1. Kamui
2. TSB
3. Tsukuyomi
