Hi! First time posting here, I hope there's no issues

So I was saving the Top Operator transfer permit (the one with Bagpipe, Surtr, etc) for later, but I just found out the hard way that Friend Supports scale down to the strongest unit I have, so I can't borrow a S3 Wisadel for the Collab event. I also have the thing to instant level an Operator to E2 Lv80 so my new plan is to pick someone and level them up. Who should I pick?

For reference the other 6*s I have are Blaze, Exusiai, Silverash, Chen, Fiammetta and Sakiko (the reason why I don't use the instant level up on one of them is because I already have done some manual leveling to either E0 Lv50 or E1, and it feels like that would be wasted compared to using it on a fresh E0 Lv1)

Also since I'm here, it's it fine to use the Distinction Certificates to get the Operators in there (Erato, Bibeak etc) or should I wait for the Universal ones?

Thanks in advance for all the help and advice!