AC is basically all I play.
I own a few sims (Automobilista 2, Project CARS etc), but AC just gives me the most lifelike driving feel that is possible through a £140 steering wheel (all things considered).
If you want to get really really into it there is a huge modding scene too where the entire sim is basically being overhauled way beyond what the original developers intended.
https://www.youtube.com/watch?v=R9gsC5vB1Eg
https://www.youtube.com/watch?v=NckNuNkbDYA