I have an Acrylic and I have to admit. At first I was afraid, I was petrified........ of scratching it. But it really isn't a problem if you are cautious. Acrylic does scratch easy, but it insulates better, it's is stronger, it is more asthetically pleasing (IMO), and I read somewhere that it is 4% clearer than glass.
Shortly after I got my tank I thought I made a mistake by going with Acrylic, but now I am a fan.