[dkulchenko]

Maybe a bit unorthodox, but I've been using SquashFS with xz for compression for long-term archival (I generally prefer zstd, but for long-term archival I don't mind waiting longer for better compression with xz).

SquashFS files have file-based deduplication, fast random access, and mountability, all of which are lacking from .tar.* archives without resorting to other indexing tools. And they're mountable on any Linux without installing anything.

Only downside is they're readonly (or more accurately append-only), but for my uses, that's totally fine.