Crit Servant

As a critical damage dealer Jalter is better because all 3 of her skills are damage steroids, one of which directly buffs her critical damage and star weight by a ton. Ozy has nothing to directly support his critical damage. You should not put them together, because Ozy's star weight is MUCH higher than Jalter's so she won't get any crits.

That said Ozy is a very effective single target rider with high attack and an excellent skill set, just not a uniquely good critical damage servant.

Ozy can be a crit servant, but he is not one. He is utility rider, he can be almost anything you want him to be and he wil do a great job at it. He is the best rider because his utility, NOT damage. There is another servant that has overall better damage than Ozy and it is Quetzalcoatl. She is a crit rider and she is better than Jalter in destroying casters (obviously), and only a little bit behind her in nuking other classes, save for assassins, of course. She is pretty underrated, literally only because she isn't Ozy or Rider Kintoki

She comes around the time Babylon comes out, a singularity away from Ozy

I don't really have much to add (all though loco-chan is better than Ozy IMO, but I don't feel like arguing that with Ozy fans) but I will say this, you don't want Jalter and Ozy on a team together. Its very counter productive, as Ozy will hog the stars from Jalter making her crits subpar. Then again, thats coming from someone who frequently misses 80%-90% crit chances.