Which one is the best choice between Intel core 2 Quad Q 9300 2.50 Mhz or Intel core 2 Duo E8400 w/ 3.0 Mhz??

Does it better if I pick Q 9300 w/ 2.50 MHZ but less speed or Core 2 Duo with more speed 3.0Mhz?

Hmm...

Thanks