Ublock is the one that was swiped from the original creator's hands under the guise of maintenance support while the original creator's time was scarce.

Ublock origin is the one to use, and is maintained by the original creator.

I'd link to sources, but it's too easy for me to cherry pick... I'd recommend looking around to see if what you find corroborates with what I've stated.

Maybe, but you'd certainly have to put in a lot of time into getting it right.