Question to those who know: I used FreeNAS and liked it, but my recent build is Unraid because I had 24 bays, and didn't want to buy all my drives at once, and

Question to those who know: I used FreeNAS and liked it, but my recent build is Unraid because I had 24 bays, and didn't want to buy all my drives at once, and afaik FreeNAS/ZFS is not super great with adding drives to the pool, especially if they are different drives. Unraid, though, is not great with drive failure and I'm starting to think I want to go back to FreeNAS, but I am torn: 1. I don't know how to move 80TB. 2. I still dont want to buy all my drives at once, is FreeNAS better about adding new drives these days?