If you are the impression that WinRAR has great compression, you really haven't tried other compressors. WinRAR's saving grace is when you distribute multi-part archives and you have a need to create par files to reconstruct broken parts of this multi-part archive. That is more or less the only thing that WinRAR does right. But with internet as it is, how often is that functionality necessary? In the days of 33k and 56k modems, that was repair functionality was handy, nowadays it takes less time to download an archive, check it against a hash and re-download it in case the hash check fails. Repairing multi-part rar archives didn't go always ok either.
Compared with zip archives, rar archives can be significantly smaller. That was what I was always told. Until I actually started testing zip, rar and 7zip. Seriously, rar could compress to 50% of what zip could do. Which is good, don't get me wrong. 7zip reduced file-sizes till 25% of the rar results. When you have data-files several gigs in size, then you really see how good 7zip is. And no, it hardly takes longer to create or extract these archives either. You are more bound to the write capabilities of the drive you extract the archive on, than 7zip itself being slow.
There are even more specific compressors out there which do an even better job than 7zip can, but creation and extraction of archives made with these compressors does take significantly longer.
For my use case way back when, 7zip saved me hours per week. Made lots of scripts that do the automatic archiving and extracting and it still saves me almost 30 minutes each time I need to create a build, pull that to my side of the ocean, extract it and push it through a significant battery of regression tests, all without manual interaction. For a piece of freeware, 7zip is practically like gold. As example: each build is about 2 GByte in size, 7zip creates a 200 to 250 MByte archive from such a build, with WinRAR I'm already happy if the archive is 600 MByte. The extra 5 to 10 seconds it takes to create and extract these 7zip archives vanish like a snowball in hell when the transfer (and verification) time is 10 minutes for the 7zip archive and more than 40 minutes with rar archives.
Archives are part of a strategy/procedure being employed for whatever your reason may have. And there are gains to be had when taking a good look at the whole strategy/procedure. Zip is the most conveinient archiver, but that one won't win you the race. Neither does rar, but that one shows a decent effort. 7zip really is much better especially if you have it dialed in.
The above has nothing to do with silly humor, so here is my contribution:silly humor - post 'em here! [warning some NSFW and adult content]