Just my thoughts on premium cv's. tiers based on amount of planes carried in real life, general size and what other ships they were comparable to within their nation.
I would have to say one of the Yorktown class at tier 8 its a reasonable step between the Lexington and Essex, it's unique from the remaining carriers with a nice history to go with them. Personally i would like the
Hornet but ultimately up to WG. I cant say anything good for the Saratoga because its 2 degrees off of the Lexington, but the again so is Prinz Eugen and hipper..... so that argument already has precedence against it.
Graff zeppelin at tier 6 for a german carrier, maybe tier 7 for balancing issues, i don't know what WG would do if they decided to add her.
Shinano would be interesting to see eventually, because she is a yamato converted to a carrier. enough said. however i can see that as a balancing nightmare.
Unryu or Ikoma class would also be nice for the japanese cv tier 7 or 8, but also akagi or kaga would be nice to fit in as well, probably at tier 8, but once again completely up to WG.
Now that they announced her, it will be interesting to see where they put Graf Zeppelin. You could make a case for T6 or T7 depending on how they implement her. It was a huge ship by T6-T7 carrier standards but her planned airgroup was tiny for such a large ship (42 or so planes). Also her final planned airgroup did not include torpedo bombers which hurts in the game. They expected to use navalized Me109s fighters and Ju-87 stuka dive bombers. I am looking forward to see if the stukas are any good.