I diy at 75/25 and have only used essentials depot VG, so I can't compare brands. I have vaped many max VG juices and have gotten a chest congestion and a slight morning cough. It isn't like the morning cough from smoking, just a quick once of, and off you go kinda thing. Heavy or tough to breath, no, not even going
through 12 to 15 ml of
juice via sub-ohm in an aromamizer all day. Things effect everyone different though.