Which 7* to rank up

Hey guys,

I've finished necropolis till the 15th. I'm at 8.1.1 and would try to get valiant in time.
With necropolis my 7* are looking nice.

But I'm unsure, which 7* to rank up or if it's better to wait for others.

I have 2 generic r2 gems and a r3 cosmic gem. For sure, I need 2 r3 champs at the end... So what do you think?

Who to rank up? Thank you for any advice