Uiua[0]'s stack model is much more annoying to work with, but I really appreciate its embrace of unicode glyphs. Every other derivative of APL throws those out at the first opportunity, but when you have a lot of glyphs, you stop being so tempted to make different arities cause the same glyph to mean wildly different things, when the arity is not actually written down explicitly and depends on whether the next thing to the left is a parameter or another function. Once you can See The Matrix, this is the chief thing that still does make K and friends objectively unreadable in a way they don't have to be.
[0]: https://uiua.org