Eve

This should come as no surprise to anyone, the "ninja" is broken. Due to her insanely high Speed base and growth, you can put her in any class and she'll do fine even in Demonic. Her personal skill is a bit unintuitive making you get a specific rune on specific weapons to really synergize with it, but other than that, she's probably as min-maxed in her growths as Tal'Dera is in her bases and growths while having better availability and more survivability.

As mentioned before, to keep Eve's base power and speed growths as high as possible, she appreciates being leveled as a Quickdraw over Cuttthroat in demonic, but any class will work as a testament as why she is an S tier unit. She will always appreciate the Solitude Ring, giving her 3.5 power as long as she's more than 2 spaces away from an ally she can bond with.

Deadeye - Deadeye is probably her best class late game when you get the Arbalest due to its Magic Rune and her personal skill. Even with a weight of 4, it has 3 higher might than the Repeater and 35 more accuracy which directly translates to 3.5 power for Eve. On top of that, Eve generally tends to have an excess of speed so the 4 weight isn't super detrimental to her. The question becomes what do you value more: more dodge or more mana to spam her personal skill to secure kills?

Slayer - Slayer is a great class on anyone who can use it due to the 1-2 range and 20% chance to hit again. You could run the Karambit if you have an extra one, although I find that Cinquedea is quite fun due to the magical trait and RNG Rune on it stacking with the Blazing Ring making the chance to deal 50% extra damage 20% - the same with Ricochet. RNG rings go hard on Slayer.

Beastmaster - Eve as a beastmaster is kinda fun because she can avoid being doubled as well as being a bulky, dodgy tank. Give her the the Love or Dimming ring for defensive bulk or the Diplomat Ring for extra dodge.

Ranger - She could do this but why lock your best unit to 1 range in a less-than-even-sub-optimal class?