I think we could separate what is real from what is realistic, when analysing a racing simulator.
IMO, LFS is more realistic and less real, while rFactor is more real and less realistic.
The realism, what means to be realistic, I think is made with those things that give the best immersion, and it starts IMO with the best response, the best feedback about what is going on with your car on the track. And this is something that LFS does much better than rFactor.
LFS would be the best if it could join the realistic feeling with the real thing, what means real tracks (with variable grip) and real cars (with a complete car simulation, like engine and brake heating, just for start the conversation), daylight transitions and climate changes, things that Simbin has made with gMotor2 for long time. rFactor is not GTR, but considering them both use the same engine, we could extend the LFSxRF comparison to LFS x (RF+GTR).