For me this is a good post thro. First I'd like to clarify myself I don't have rFactor, and only played LFS for around a month. I'm still new to LFS, but not games, especially simulation games.
I'll just take this post as a review for both games, but not a discussion for me, coz I know nothing more than u guys. However, personally I think that the most attractive point from rFactor is their mods, and what people can drive a real car in a real track, of which you can never experience this in LFS (at least at this moment or coming few years).
I've played racing games for years, TOCA, NFS, GT series(PS/PS2), much more that I can't remember. In the first time, I am addicted to LFS, but my DFP right a way to enjoy this simulator( personally I dun really treat it as a game ). I'm a racer in real life, kart-racing, and also tried formula, etc. I love racing, and what LFS can give me is the feeling. Nothing is perfect, so do LFS and rFactor. There are still much more rooms for them to improve, maybe in a slow way, but we will wait and see, won't we? Just because we all here love racing. Right?
Cheers.
keithano