I am not an audio professional and I personally am not in love with the interface in my limited use of the thing -- though my basis for comparison is only much-simpler software packages -- but I have consistently seen Ardour recommended as a DAW under Linux.
If you have not considered it, I'd probably at least have it on your list to look at.
Yeah as someone who's been producing for 6y I haven't looked into LMMS a lot but that's also because I did not really like what I saw particularly. Ardour looks a bit more robust.
There's the argument that you can make every type of tool have the same effect if you use it properly, but imo it's a big difference in the end. So plugins will always be a bit of a struggle for compatibility in Linux (I'm sorry Linux power users, but I've been there and had to go back). Otherwise it might be a viable option.