I'm disappointed in all of you.
My vote goes to Van Halen.
Although I love ZZ Top as well, Van Halen is close to the top of my list with Led Zeppelin and Pink Floyd.
The two bands are extremely hard to compare because both were great bands of their time, but played totally different music.
But of course, me being a metalhead, I enjoy more of the "early metal" sound of Van Halen over the blues/country sound of ZZ Top, as I for one, despise country with a flaming passion.
In case you all didn't know, but DayCee does, Eddie is at the top of my list for guitarists. Not only is Eruption one of the best guitar solos ever, but Eddie is just much greater than any other guitarist on the planet, in my opinion.
Also, Van Halen progressed and evolved so much with society's needs, with finding a new lead singer.
Van Halen gets my vote.
P.S. Sorry I had to cut that last part short I'm getting busy.