The best rock of all time comes from ACDC. The best generation of rock is the 1980's. The thing that all of this has in common is hard rock. Classic rock was for a more simpler time for more simpler people. Hard rock is for the current fast pace generations.
The classic rock is a time limited rock whilst hard rock is a genre of rock which can be from the 70's till now. It is the musical characteristics that sum up the genre instead of lots of genres mixed in together to create a classical rock, Which even contains the disco musical characteristics firm the 80's.
Classic rock is better because it encompasses a much wider variety of the rock genre. Hard rock is typified by very strong beats, elaborate guitar and drum solos and, what are sometimes considered, innapropriate lyric. Class rock, however, embraces a much wider variety. Anything from the 1950s to the "hair bands" of the 1980s can fall under the classic rock definition.