Without a doubt, the most elegantly designed products I've ever used are the sequencers and synthesizers made by Teenage Engineering (https://teenage.engineering/). I own the original three pocket operators (PO-12, PO-14, PO-16) and every aspect about them, from the packaging to the board design itself (the whole instrument is just the PCB its made on), is a work of art. Granted, they're not necessarily the most intuitive thing to use, but when you consider TE has shrunken a desk's worth of electronic music equipment into something the size of a Raspberry Pi, it's hard to not be impressed with their design methodology.