B.M.
I'm with Sprint and they still upgrade every 2 years. Based on my research, in my area, it's still the best price per month with only 2 of us. My sister is with T-Mobile and hers is cheaper with 5 phones on the plan (their per phone add on is less). Sprint has the iPhone now. I'm debating between that and the Samsung Galaxy S2, which my nephew has and loves.
On a separate vent, I will never understand why phone companies treat new customers better than long time customers. Why do you give discounts to someone new and not to someone who has shown loyalty? Drives me nuts.