I like Ollie and agree her high energy is infectious and she's affable as fuck. However, she has her own problems that aren't external and needs to deal with that and grow up before she takes anyone's mantle. She's obviously really young and in the process establishing what kind of lady she'll be for either a long while or the rest of her life. There's also more to Coco than the superficial traits in your shortlist, which is why her upcoming departure is a huge blow to Hololive. Take a nice peek of Coco's wisdom, I don't think any Holo can readily take up her mantle just yet:
https://www.youtube.com/watch?v=dOPmdqaz444 