What is the most suited craft essence?

It really depends if you don't have a way to generate crit stars reliably, then it's better to go with the sumo. Riders have high star weight so if you had a way to make stars the +20 crit strength would go far.

Golden Sumo is a flat attack steroid (think permanent Charisma buff) that will apply to each of Ozy's cards, as opposed to Victor of the Moon which only enhances Buster cards. On top of that, it also gives a starting 50% NP gauge.
It's a great CE for general use. I don't think you'd want Victor of the Moon over it unless you can get Ozy to Crit all the time.
Just a sidenote, but if you also have Origin Bullet (Kerry CE), it'd be perfect for him. 30% Spec. Damage against Casters means all of Ozy's cards will feel like a Buster chain against said class. It doesn't have starting NP gauge and the Invin. Pierce is forgettable, but it is great on him nonetheless.