A lot of people like the Silhouette (and I believe there are some others, but I'm drawing a blank on what they're called) better than Cricut because you can use third party software with them. Provocraft sued the software companies so you can't use programs like Make the Cut and Sure Cuts a Lot with the Cricut.
That being said, I have a Cricut and have good success cutting fondant, gum paste and icing sheets with it. There's a lot you can do with it... much more than just cupcake toppers. And there's tons of discussion about cutting machines in the Cake Central forums.