GTC: It offers some very close racing in pedigree sedans beating all hell out of each other. Luxury sedans and humble coupes alike compete voraciously, flogged on and on by their driver to take the respective title, a national award in the sense that while German cars are raced, the drivers come from all over the world to compete. The whole thing sounds very different from F1, and a lot simpler and yet more fun to watch on the track than in the courtroom.
I don't follow A1 GP that much, but I'm sure it is an excellent race series.
Other than that, my vote is for the WRC.
Rolex Sports car racing is an even better concept, what with the thrifty (but far from frugal) technologies and machinery used in the championship.
