If you're not intending to use complicated RAID setups, just go with btrfs. There is no reason to bother with zfs given your specs and needs.
Do not go with ext4. Unlike both btrfs and zfs, ext4 does not do data checksumming, meaning it cannot detect bit rot (and obviously cannot fix it either). You'll also be missing out on other modern features, like compression and copy-on-write and all the benefits that entails. Once you start using snapshots for incremental backups using btrfs send (or its zfs equivalent), you'll never want to go back. Recommended script: snap-sync.
If you're not intending to use complicated RAID setups, just go with btrfs. There is no reason to bother with zfs given your specs and needs.
Do not go with ext4. Unlike both btrfs and zfs, ext4 does not do data checksumming, meaning it cannot detect bit rot (and obviously cannot fix it either). You'll also be missing out on other modern features, like compression and copy-on-write and all the benefits that entails. Once you start using snapshots for incremental backups using
btrfs send(or its zfs equivalent), you'll never want to go back. Recommended script: snap-sync.