Not a huge fan of either but saw Skynyrd 2 years ago after a baseball game. I'm guessing 90% of people here can name their set list. Favorite song is "That Smell". Of course the original 1970s classic.
Saw ZZ Top last year with the Doobie Brothers as supporting act. Gotta say, the Doobs rocked the house while ZZ Top looked and sounded like they were just going through the motions. I hope you will see a better show.