I currently have a secondary pool (with raidz2) that I was originally going to use for my important documents, such as storage for Paperless-ngx, as raidz offers corruption detection and repair. The pool is encrypted.
However, I’m concerned about rebuild times (it’s a pool of 4 22TB drives). Is btrfs a better choice for this use case, or should I just go with raidz like I originally planned?
For your situation I would be more likely to go with a single drive with btrfs and dup for metadata redundancy. Regular snapshots and scrubs.
Use a second drive in the same system with btrfs to store snapshots at wider scheduled intervals. These will be bigger since no CoW on the separate file system. Scheduled scrub here too.
Use a third drive with ext4 as a backup target using a separate backup mechanism.
Use the fourth drive as a spare, or in a separate location as a target to send the backups if you don’t already have an off-site solution.