The BTRFS thing is cutting the power or losing the disks in the middle of a write which corrupts your data. If you don’t think that will be a problem then BTRFS is fine. I recommend ZFS personally, but it sounds like you want to use mdadm instead so basically anything will work.
If you might need to shrink your filesystem later then avoid XFS. EXT4 is relatively featureless but ol’ reliable. ZFS is good for long term data integrity and protection. BTRFS is similar to ZFS. BcacheFS is new but like a swirl of EXT4 and BTRFS. Just pick the one with the features you want.
ZFS doesn’t require a lot of RAM, but it will use more RAM if it’s available. 32G would be plenty for a home setup. I think my home file server has 24 or 32G of RAM and ZFS. If it’s important data then stick to what you know; there’s nothing wrong with mdadm.