Hundreds of Models to choose from, you surely need a mechanism for choosing a right model. Android OS 2.1 will make sure you get lakhs of free open source apps to use. But if you choose exclusivity go for Apple I- Phone . Paid apps are surely going to feel and work better than open source. Apart from that 1 GHz processor is a norm today witrh at least 8 GB of memory for HD video recording and uploading to youtube support for instant sharing of videos to your friends.
5 MP of Camera would suffice for most. Multi touch capacitive screen is used for finger touch control, is also a must. Also look for style qoutient and your favorite social networking apps preloaded would be an added plus. Also look for your budget constraints and choose a I-Ihone ,Samsung or HTC or a BlackBerry Model.