Question About Lenses

Alright, I’ve been scouring the Internet for the past few hours looking for the best lenses for a Canon EOS-30D. My searches are coming up mixed, so I figured I’d see what you all have to say on the subject. Basically I’m looking for a lens with extreme versatility and, if I must, a separate lens that can shoot in low light environments. As many of you know flashes ruin ambiance and I prefer to use one as little as possible. So what say you, learned readers?