It's 2022: if you need to get an ipad 10" or ipad 8" mini, what are the oldest usable versions?

ipad 10" ipad 8" What used oldest model should I get? How large of capacity should I get? 10" get an ipad air 2 or newer oct 2014.. include ipad pro's, ipad 5,6,7,8,9..etc 8" get an ipad mini 4 from sept 2015.. or newer includes ipad mini 5,6 What storage size should you get? At least 64gb if possible. ios already takes 10-12gb of storage. If it needs to do a large update.. it might need even more storage. In the past I had issues updating my ipad because of this... let alone fixing the ipad with an update.