They have their pros and cons, which you guys have brought up already. I like acrylic for large tanks and glass for small tanks. The large acrylic tanks are so much lighter and easier to move, safer in general, and in the event of scratches, you can buff them out. Glass (rimless) tanks look a little better to me, but due to the weight, breakability, etc. I only really like smaller glass tanks.
The only tank I've ever had fail on me, was glass. Though I have only owned acrylic tanks for a couple years, so I guess we'll see.