I, like HisGem have both machines, Kenya gave a great comparison list. I think it all comes down to money. Do you have the money to be buying carts when you need/want certain cuts/design?
If I had to choose one, it would be the Cameo(Silhouette)
That being said, I still love my Cricuts and all the carts, and actually use it more than my Silhouette, for now! I don't think I will ever stop using my Cricut. But the Silhouette just makes more sense money wise.
If I could remember what I paid for each of the carts I bought and added it up, I would probably have a mini heart attack.
Or at least my husband would!