Slightly cheating as it makes no music on its own but the clear winner for me is the Blokas Midihub. It’s so good I feel it’s almost an essential in every electronic music setup. It’s a major upgrade to every piece of midi enabled equipment.
I mostly only use it for routing, splits, Digitakt polyphony and transforming values but the other day I made a sequencer on it (see LFO note triggers that no one cared about sad face) and people have built hugely complex things with it.
If they made one (same size) with a tiny screen, four internally assignable buttons and encoders and maybe a battery it’d be even better but even on its own it’s ridiculously useful. And the editor, patchstorage integration is easy to use.