Which T-mobile device should I pick for someone new to smartphones?

I'm looking to upgrade my parents from their old flip phones to something more up-to-date. I personally use a rooted vibrant, looking to make the move to the nexus 4 when released, but I believe for some people android requires a learning curve, I haven't used WP and am familiar with iOS and BB, but what device in your opinions would be best suited for someone not familiar with the smartphone concept, something easy to adapt to?