I personally like the Las Vegas CSI theme better. I don't know if any show can beat Pete Townshend and The Who's "Who Are You." When I watch the series I just have to listen to the opening theme.
I like the CSI Miami theme, too, but to me it doesn't acheive as much greatness as the Las Vegas theme.
What do you think?

As a child of the 60's and 70's I gotta go with the WHO. Doncha just love it! LOL

I like The Miami one a bit better even though the Vegas one is very catchy!