Not OP, but I use Bitwig. It's well worth the money.
Reaper's also worth a look if you're primarily recording, but it does have some MIDI capabilities.
Ardour does actually not have a good MIDI experience ... this will change with the upcoming 7.0 version.
The MIDI experience overall doesn't have anything to do with Jack
What are some of the problems y'all have encountered with its MIDI experience? Seems to be alright for me, though I ain't doing anything particularly fancy with it.
I currently use Bitwig because it's the only Linux-native DAW that I can grasp. If Ableton released a Linux version, I'd probably switch.
Interesting you and others use Bitwig, which I've never even considered using before. Maybe I should pay broader attention.
It is quite pricey (or you can buy the cheaper 16-track version) and still missing some substantial DAW features, so it's not an obvious choice.