Yea man, hard to choose the best one. Eruption would be obvious, Panama, Really got me now, etc.
He did the guitar for Michael Jackson's Beat It (from thriller album I think). Listen to it, you'll hear some pretty hot licks throughout, especially at end.
I loved the old van halen when DLRoth was with them, but Roth was kind of an ignoramus in the videos I thought. I'll be they were happier when Sammy Hagar joined them.