Well, understand that it doesn’t really play like a Souls game at all. That said, I’d probably just wait for the new one if you’re excited for it. If not, either AC4 or AC5 would probably be the way to go. The early games didn’t map camera movement to the right stick; so, I would avoid those as a newcomer.

AC4 plays a lot more “super robot-y” than the other games. AC5 has much smaller mechs by scale which makes terrain and cover much more important tactical considerations.