I use this:
Amazon.com: Apex Products 35104 Rock Doctor...
I'm fairly happy about it. Granite is tough to keep streak free. I think you'll be very happy with this product as it creates a wonderful shine. There is also a granite polish made under the same brand. The smell is absolutely wonderful and will make your whole kitchen smell amazingly clean!
Oh, i just read the reviews and someone says it has an unpleasant scent. Hmmm....