I digitized my studio a few months ago and settled on Reaper (running on kubuntu 20.04). I'm pretty happy with it, though Linux support is "beta" and support is forum based (there's a couple bugs that I'm just living with because nobody's engaged on them in forum posts).

I probably could have gotten away with Ardour for my needs (recording, editing, mastering) - however, I can run Reaper at lower latencies (via Jack configuration) than Ardour. Mixbus seemed promising, but requires more latency still. Bitwig is cool, and I'd happily pay for it, but their midi implementation on linux is pretty weird, and I don't have the patience to fiddle around to make it work. I haven't used Ableton, so I can't comment on comparison; there is a plugin for Reaper which gives it a live performance mode apparently along the lines of Ableton's, but it's mac/windows only.

Anyway, Reaper is extremely featureful, and is only around a 15MB download. Good midi implementation, customizable, good range of bundled effects (and ability to write your own in javascript). There's an audio engineer who posts tutorials on youtube under the name "Reaper Mania" - check out the recent ones to get a sampling of capability / workflow.