I have noticed that 7-zip offers the best compression ratio out of the options you listed above when set for maximum compression. I personally am happy to hear this news.

Better than xz?

And what's the difference? I alwasy though 7zip was a bit sketchy like rar archives, zips are more common on windows and on linux everywhere I see there are either gz, bz2 or xz.

xz is based on LZMA, which was originally introduced by 7-Zip.

xz is a much simplified version of the massively, insanely over-engineered and frankly impossible to implement 7-Zip format.

xz doesn't have BCJ2 (though it does have an earlier BCJ filter), which allows for somewhat better compression of exes. BCJ2 produces separate streams which independently compress better. See for instance https://bugzilla.mozilla.org/show_bug.cgi?id=1514357, saves almost 10% on a Firefox installer (which uses 7-Zip) vs the complete update .mar file (which uses xz/liblzma).

Keeping the options for those straight is why one of my most used command line programs seems to be atool.

https://www.nongnu.org/atool/

I like the current bsdtar-- it's libarchive [1] based, and supports a bunch of formats (including your typical tarball formats, but also zip, 7zip, and rar archives, amongst others).

[1] https://www.libarchive.org/

I'm assuming it's because 7-zip (1) has widespread use on other platforms (2) supports solid compression and (3) is efficient for randomly access. There is DAR which does (2) and (3) but not cross-platform and is already esoteric on *nix platforms.

Those don't use LZMA. For LZMA there is 7z, xz, and lzip.

Also pixz, which can use multiple threads for decompression.

I spent some time a year ago comparing formats, and ended up liking pixz the most, especially being indexable. EXCEPT that according to my notes, I couldn't find any gui archiver that worked with it. Do you know if it is still that way?

I've only used it from the command line, so I don't know. For my needs, the ability to use multiple threads for decompression was its killer feature.

lrzip :-D

tar supports xz and even zstd now, but it's not clear those are better for all purposes than 7zip, especially since .7z is more likely to work on other OSes than .tar.compressionextension

xz is almost identical compression depending on flags used but lacks encryption. Some people use 7zip to also encrypt their files.

Brotli. My new goto.

Being indexable is my own favorite reason.