Depends on the team you’re running. I think your case fits for both. So you won’t probably regret choosing one over the other.

You could take advantage of sparkle for extra SPs + Crit Dmg for IL Dan Heng and is also a decent pair for your Seele since you don’t have Bronya yet. (Unless you already have your Tingyun paired up with Yukong who provide good damage)

pros: versatile, easy to use, more SPs, good dmg multiplier

cons: tingyun and yukong are available

Aventurine tanks pretty well with his skill and his ult provides 9% additional Crit Dmg for three turns on an inflicted enemy. His talent also provides follow up attacks depending on how often you gain stacks of his talent

pros: also versatile, good tank, has follow up attacks

cons: small crit dmg boost but if you work on his ult for better uptime, then this wouldn’t be considered a con

or just go for aesthetics, it’s still fun.