I’ve now further upped my experience with OnAir by flying with Self-Loading Cargo (SLC) add-on on passenger flights.
The two add-ons perfectly complement each other to be honest. For those of you who don’t know SLC simulates cabin and pax management. U now gotta watch your angles, speed, and landing to score a good rating.
The two don’t integrate of course so it’s a bit of legwork to set both up before your flight.
One disadvantage of SLC is that I feel there isn’t much focus on MSFS. They haven’t grasped and capitalized on new wave of simmers like OnAir did.
I recommend anyone interested to give it a go. As an added bonus challenge you can couple it with A32NX mod. Good luck operating an FBO on London City (EGLC). I crashed so many times on takeoff in fully loaded A320 
PS. Having to run all these add-ons really makes me sad MS didn’t include a proper thought out career mode. Either buy out or copy what those add-ons are doing and have it in vanilla game. As other poster said, if it wasn’t for these add-ons I’d have put down MSFS already after some sightseeing. I need to be told where to fly and for what purpose. Imagining everything in my brain (“ok so now I’m gonna pretend I’m a Lufthansa flight from A to B”) just doesn’t work for me, and I imagine many other players. Such missed opportunity by MS.