The one critique of F1 is the lack of passing, the straight dominance of just a few teams. Not that any driver can win a NASCAR race, but only very few have a realistic chance of winning an F1 race. Most drivers are in serious competition for places 5-10, than they are 1 through 3.
But as far as driving goes, and the technical mastery, F1 is a much better product than NASCAR. The races are shorter as well, which is a perk as it frees up more of the day. NASCAR will always have the wow, OMG IS HE STILL ALIVE! factor though, just due to the cramped racing conditions and forced parity between the cars.