Best cell phone and provider for unlimited calling and texting plan?

I will soon be moving to the USA to attend college this fall, whilst my family will be living in england. I am looking into pay monthly cell phones which have an unlimited calling and texting plan. As i will be traveling back to England during the holidays this phone needs to be able to work overseas. I am interested in getting an iPhone or Blackberry as i hear they are popular and they have good reviews. Any ideas and opinions on which cell phone and monthly plan i should get? How much would this cost? Thanks
Because i will be overseas from my family i am interested in knowing if there is an international texting plan available.