Second the Bitwig, with a caveat: Read the Manual or Suffer. There are a alot of absolutely non-obvious UI rakes you can step on, can be really off-putting if messing around blindly (from the top of my head: if you accidenly turn on clip player for a track, it will not play the timeline; not disabling polyphony will prevent your Note Grid from running continuously; microtonal notes are being sent to MIDI differently depending on the MPE settings ...)
Bitwig + Pianoteq is the ultimate toy to tinker and relax with.
Bitwig + Pianoteq is the ultimate toy to tinker and relax with.