In our old review the Petzl Reverso 4's predecessor, the Reverso 3, was our favorite belay device for multi-pitch climbing. Both are tube designs with auto-block capability that function well at belaying a leader, rappelling, or top roping. And the four is even lighter and better. However, we now just barely prefer the Black Diamond ATC Guide because it's smoother when belaying a follower off an anchor, and more durable. That said,the Reverso 4 is an ounce lighter and if you use skinny ropes, it might be the better option.
You can check out nine other devices in the complete Belay Device Review.