As a sibling comment pointed out, Reaper is not FOSS, it's fully proprietary. What makes it stand out is its great Linux support, and very generous licensing.

If you want to venture into the FOSS DAW realm on Linux you have to go to LMMS and Ardour. I've played around with them, they're a little bare-bones, but they do work. Issue is I haven't been able to use them properly, because I just can't stand to look at them, they are afflicted with the medium-size open-source project curse of looking particularly horrid. I hope this isn't taken as an affront to any of the developers behind these projects, a DAW is a hard task, but I keep asking myself, out of the set of developers who work on these projects, is there really no one who feels the same way as me? Am I just afflicted with some weird pixel-peeping autism-esque disorder that makes me stare at the constantly-reocurring-throughout-all-FOSS-applications clump of jarringly gradient-ed grey buttons with white icons on them, their round corners contrasting with each other because they're clearly placed way too close together than they were meant to be? (I swear I see this in every mid-scale project using QT and older GTK!)

And I also need to confirm, this isn't just a "slight annoyance" for me, I have genuine issues when I have to concentrate on a project within some application that is suffering from the FOSS UI affliction, my mind wanders to looking at those buttons again, or those #00FF00 greens, or at some label that has clearly seeped a few pixels downwards out-of-alignment with the button it was placed in...

Ugh, I know I have some issues for sure, but I know someone else has to care about this too? It's the main reason why I fail at using non-textual FOSS software, and have to resort to Logic Pro or Ableton!

Sorry for the rant, I had to get it out of me. I wish I had more time in a day, then perhaps I could go to these projects and help out with UI, but I have a feeling my proposals will be rejected, even if I had the time to make them, I have found most FOSS developers are quite happy with how their UI usually looks like, including many people here on this forum.