Well, whilst I still don’t think that there is much to be gained by a standard comparison, here are a few pointers.
They both have slightly odd shaped handles. I like the Supply but I am not so sure of the Oneblade Genesis. That is a really odd handle. By the way, I don’t like the Core for several reasons. So I don’t include it here.
They are both solid and well-engineered. No preference.
They each have a “buzz”. The Oneblade has a pivoting head. Mine doesn’t pivot a great deal but I guess it may loosen. The Supply has alternative heads. Both buzzes are fairly cool.
There is a grand choice of one blade for the Oneblade (!). This is a particular Feathers so it could be worse. Connaught have them, for UK shavers. Supply takes the two main injectors and, with a little effort, one of the Proline blades which are fabulous and, if you are keeping count, gives the Supply a huge advantage.
The Supply is fairly simple to pick up and use. The Oneblade needs a little practice.
The Supply is reasonably priced. Oneblade is frankly expensive. No one said this hobby would be cheap!
And the shave? The Supply is excellent. I am still getting to grips with the Oneblade but it is delivering Knick-free shaving so far.
It depends on what you want. I may sell one of them in a while but for now they are fun! And that is pretty much what I want.