I’m in a similar situation, as I have a maxed Seshat and recently acquired Khiona. I decided to ascend Khiona rather than other 5s purple in my bench because:
- the other purple 5s I have suck;
- I like Khiona’s attack buff
- I like the fact Khiona is a rogue, meaning she has the chance to dodge specials from opponents. And I have all the Rouge emblems I got since they introduced them waiting for a worthy hero… she will be the one.
- If I were you, I’d go for Khiona also for variety
Edit: also, there aren’t many “better” (more different than better) 5s purple you could get: Kunchen, Black Panther… another reason to go with her.