iPhone Carrier?

I was wondering what carrier I should choose for the new iPhone. I currently have Virgin Mobile which has terrible service but it does have the iPhone. I do not own a iPhone but my birthday is coming up. My usage would be wifi in the morning until about 8 then my phone would be turned off until 3 then coming back on for music and texting and calling. When I travel which I have to go to meets, I would be on the internet and posting pictures to Facebook. I would like to have unlimited calling, and unlimited texting. But I do not know what data plan I should get.