I'm not sure if this is already a thing or not but the ability to open audio files in a external editor would be killer. Like being able to right click on a clip or clips, select open in a "external editor"; such as audacity(or one your choosing) make edits and then bring edited audio back on tracks. Reaper has that feature and it is awesome when I record vocals and need to do some noise reduction and remove clicks and pops. May be asking a lot for a free DAW but some advance features like that would knock Reaper out the box for me; being someone who got started recording in Sonar back in the day.