The format (used by 7-Zip ) is widely considered one of the best choices for archiving a "long report" or large document sets because it typically achieves a significantly higher compression ratio than standard ZIP files. Why .7z is "Good" for Reports

: For text-heavy reports and documents, .7z with the LZMA2 algorithm can often shrink files to a fraction of their original size, far outperforming ZIP.

: LZMA2 (best for modern multi-core CPUs).

: It treats multiple files as a single continuous block, which is highly effective if your report consists of many similar documents or revisions.