Maximize file system usable space for a mostly read-only data partition

I'm trying to wrap my head around all the different (common) file systems available, but I can't decide which one best applies to my scenario. My use case is: 1) The partition is for data only. System files are in a dedicated drive. 2) Each directory contains a big ISO file (movie DVD or BD - anywhere from 5 to 100GB) and 4 very small files (e.g., a text nfo file and a three jpg images). Files will likely never be deleted, with a few rare exceptions. 3) I'd like to maximize the usable disk space. I tried formatting a 3.6TiB partition with ext3, removed all the space reserve for root, but still got a significant (for me) space loss relative to a partition of the same size formatted as NTFS, approximately 57GiB. If I understand it correctly, this is due to the pre-allocated inodes (is that an accurate term?). I don't like the idea of tens of gigabytes sitting there unused, waiting for files that will never come. 4) I'd also like to avoid NTFS partitions. I don't like their performance under Linux (writing big files to ext3 was 6-10 times faster than NTFS in my test). Things I don't care much about: journaling, COW, snapshots. This partition will be pretty much like ROM, or an archive, if you will. If there's a failure when I'm writing the files, I can start over. Please let me know if I'm missing something here. Now, between ext4/3/2, btrfs, xfs, zfs, which one would be most appropriate and why? Should I also consider extFS or F2FS? I haven't read much about these two. Note: I've found this similar question , but it's from 2016, I suppose answers would be different now. Thank you, VMat