Rfactor is more of a sim than what you're playing yeah, but if you're fast in those games its only a matter of practice to get fast with a sim, theres an adjustment period but its not too harsh. Rfactor has the benefit of an absolutely massive ammount of free content available, cars and tracks and different series, but the quality of those mods is very specific, ranging from amazing to quite bad. The game without the mods is very lacking, so the whole strength of Rfactor lies in the extra mods, some of which are exceptionally good. The online racing however with Rfactor is not great, unless you're signed up to a league you won't find a whole load of online action, but its definately a must have game for any racing fan.
IRacing is the only racing game i play online at the moment, its specifically made for online racing though it can be expensive as each new car/track costs money. The quality of the content is top notch but you get what you pay for, the quality of the online racing system is also top notch, though the ranking system means if you want to drive the fastest cars in races you have to prove you're a clean/safe driver to earn licences, if you crash a lot during races you won't advance, but it is by far the best online racing experience due to its design, and there are always races taking place.
Otherwise you can always stick with F1 2010 for online racing which is hugely popular, or for the more arcade experience theres Need For Speed World.