I was an early beta tester for RFS when they first released it to the public. Wasn’t a huge fan, but it definitely had its advantages over IF, and they seem to have improved it a lot over the past few years.
If you want physics, you don’t play on mobile. No sim on your phone or tablet can compare to the physics of a PC based sim.
I haven’t played IF in over 2yrs, and from what I remember, the biggest advantage that IF has over this is the ability to make a customized flight plan.
Yes, IF has more consistent aircraft textures, but a.) it takes them a very long time to release a new one (RFS seems to frequently release new planes), and b.) the aircraft that still looks pretty dodgy in RFS are from the beta, and the textures were carried over from their airline manager game.