I dunno. Nascar is doing a lot of interesting stuff. New Next Gen ares are pretty interesting. They are doing plenty of road races, and this weekend is a dirt race in Bristol which should be fun. Every track is pretty unique and I like the way they break the races up in stages and the points system for Nascar is better imo. Also, I like that there are more cars on the track. More racing to see.
I watch both and I feel like Nascar is more fun to watch. But I think part of it is the drivers aren't afraid to mix it up. There's some of that in F1, just not as much.