iRacing is a very good simulator, but the community just does not have the great feeling you get at LFS online.
LFS has cruise, buildable objects, fun, racing, drifting, etc.
In iRacing you can only, or race offline with your BOUGHT cars and tracks. Or try to get a higher license online before you can drive with others. This takes for some users ages of times, and then it bores them. Also iRacing costs monthly and LFS is something that stays.
So overall LFS is still better.