In general you wanna keep orb-changers with hast for systems teams down the line. Also powerful boardchangers ala Urds.
4x Australis is just nuts...thats alone 20 rows. You could run a crazy Perseus squad
Invest in Sumire - she is great and also very good sub for herself.
You can probably get rid off - 1x Muse, 2x Grodin, 1x LMeta, 2x Ra ( i would keep the other 3 for farming stuff like Tamadra Retreat and PreDRas), 1x Goetia... and i would probably keep the rest for now. You probably can get rid of 2 LKalis, but i would keep them just be sure, they might be useful once we get the 2nd active skill update.
At the end obviously it depends on which teams you wanna play...but the ones i mentioned are safe to sell without regretting it too mich - imo.