AC/DC with Bon Scott (get out the calculators, bitches
)
RUSH on the Signals tour was so great, but on Grace Under Pressure I got to stand against the stage so it was possibly better.
Neil Young at The Cow Palace was really great, too. It was the "third best garage band in the world" tour so there were giant props like Live Rust, but different. Also he sang a song called Mideast Vacation that hadn't been released yet. They must have played it for about 12 minutes. It was excellent and I really liked the opportunity to hear something I'd never heard that I really liked. Later it was released on one of his mid-80's Geffen records, and while I liked the recorded version it paled to the live version.
I really like seeing RUSH, but Neil Young's Live Rust record is the reason I learned to play guitar.