Not to claim any are better than Dyalog, but there are options: https://aplwiki.com/wiki/List_of_open-source_array_languages . I think dzaima/APL and April are both all right. Personally, I think GNU is not a good design: for example it has no lexical scoping or even control structures, essentially requiring you to use goto for program control. BQN is my own effort and I would say it has more serious ambitions than these. If you're not attached to the APL language specifically, I'd take a look.