iPhone 4S. I've had my iPhone for 1 year or so now and I love it. It helps me greatly when I'm driving or when I have a question, Siri helps. I suggest iPhone. But as Magicman said, it's my personal preference. So do what fits you.
I don't have Windows 8 but I did have Windows 7 and let me tell you, from the looks of it and from what I've seen, I wouldn't get it. I honestly think it's such a waste. Windows 7 is my favorite in the whole Windows line and it always will be.
Honestly, I love what they did with it. It's not getting the good reviews it deserves, but I personally enjoy having it. 1. I love how it's so white. It matches my phone. 2. It goes a lot quicker. 3. It doesn't take that much space for me like everyone else says 4. I love the transitions they added, so now it fades out 5. It's so simple