honestly , the only evnet units that i'd rate higher (either because of stats or simply general usefulness) then karma are :
anya - super tank that can be healed. She also attacks 2 targets at once post aw
odette - if you get unlucky with plat mages , you're pretty much screwed , and have to rely on cryus or barbi. Maybe mehlis , but shes quite a bit weaker then plat mages statwise as well
Imelia - 1 of the best duelists in the game atm
Claudia - if you get unlucky with a princess , she can be useful
Solano - great aoe magic dps , at very low cost.
And out of this 5 , odette and claudia are on the list simply because they are so general use and easy to obtain compared to their premium counterparts.
And i'd argue that Claudia is debatable since there are duelists that can replace a princess