It's not AI based but I use Cthulu to do this. You map chords to single midi notes, and there's an optional arpeggio/melody sequencer. The neat thing is chords

It's not AI based but I use Cthulu to do this. You map chords to single midi notes, and there's an optional arpeggio/melody sequencer. The neat thing is chords don't have to correspond to they note they're mapped to. So C2 can be an Emaj, C#2 is Emaj9, D2 is Esus2, whatever you want and there's lots of premade chord packs from the community in every key and various styles. I like the Bach inspired ones. Because there's no relation between the note you play and the chord mapped to it, you can just noodle randomly without thinking of what you're pressing and just use your ears.