as a man who is active in sim racing for around 5 years I can tell that Assetto corsa is best all around sim title. Many things work right and the realism with mods Pure or Sol and CSP is on completly on another level. Paid mods keep the sim alive becouse most of them are on par with AC cars and some of them even better with advanced physics from CSP. I love rFactor 2 becouse it's hands down most realistic sim but it has it's own flaws. It will be interesting to see what Assetto Corsa 2 will bring next year. If they allow modding and give tools to modders then sky will be the limit!