Every book before Underworld is more like White Noise than they are like Underworld. Libra is probably the best one. If you like (American) football, then "End Zone" is good.
He's probably my favorite living author (although to be honest I mostly read books by long dead authors). I've read a few. I think Libra was the best one. I also read Falling Man, Cosmopolis, and The Body Artist. He has a wonderful writing style.
I've been trying to get through Ratner's Star for years. It's not bad but I suppose it's just not the most compelling.
Libra is great /if/ you are interested in historical fiction - specifically focused around the assassination of JFK. Mao II is one of my favorites, examination of terrorism and political violence, psychology, meaninglessness, etc...If you want something totally different Zero K is basically sci-fi.