I regularly saw ARJ archives on PC BBSes in the mid 90s, next to LHZ which was most popular. At the same time the Amiga world was (and I think still is) dominated by LZX, which supplanted LHA.
Which is surprisingly powerful as it does various data analysis and compression testing of files in order to pick the best method, and often coming up with fantastic results. Though I'd be surprised if it has a mentionable user base these days.