Good luck trying to send a file compressed with Zstd or Brotli to people and have them know what to do with them. I’d certainly have to google to figure out how to open one of those. And I’m an engineer and aware that those formats exist.
You don't really need to have support for a particular compression fromat in the tar command since the tar format does not support compression at all and instead the output of tar is passed through a compressor such as gzip or xz that has its own encapsulation format. All the support in tar does is add switch to start that (de)compressor for you and, for GNU tar, to detect it based on the file extensions.
https://www.opencpu.org/posts/brotli-benchmarks/
Distributions have stopped using xz/lzma in favor of slightly inferior (size-wise) alternatives due to the time and memory decompression requirements of lzma.
In fact, better compression with LZ formats often means faster decompression (at least compared to other settings of the same format) as there is less compressed data to pass through the expensive entropy coder (which itself has symmetric cost for encoding and decoding).
For zstd or brotli I can't even name a GUI program able to open them outside a somewhat obscure 7zip fork.
(The best bit is that the official WinRAR Linux distribution is a .tar.gz)
Just use ZIP unless your classmates are working solely via tethered 2G connections in Tierra Del Fuego.
If sending gigabytes of text please use lzip ;)
I had to look up lzip.
https://en.wikipedia.org/wiki/Lzip#Application