[lifthrasiir]

> Does anyone know why RAR is better compression-wise than the two more modern standards?

It simply uses a much slower algorithm (prediction by partial matching, PPM) in the highest setting. Those modern standards are designed to be fast enough and improve the status quo in that performance target. If they were only concerned about the compression ratio there are tons of other algorithms that would handily beat RAR already.

[sumtechguy]

7zip also has a ton of settings where you can get it in the same ballpark of compression ratio. But LZMA2 usually consumes more memory to do better. It also takes a decent amount of time the more you fiddle those settings. The defaults on 7zip are fairly tame but 'good enough'. I found in my cases if you turn on solid archiving and duplicate file matching you are usually just as good as RAR or usually better. But costs speed.