I went for the 'emulate a cigarette' route initially. In my case a 601 and my wife a 401. I now have a Protege and am far happier with it. It's partially the extra battery life, which is awesome, but it probably has more to do with the 510 atomiser which vapes like a fog machine!
I still use them both; however, and get enjoyment from them both. If cost isn't an issue, I'd endorse thewomenfolk's suggestion and go for both of them. Half the fun is watching your friend's expressions when they see the e-cig for the first time. They tend to be more impressed with the looks of the fake cig than the suspicious looking '....', as they call my Protege.
A few of my friends have ordered their own but all have gone for the ciggie looking device rather than the Protege, despite the obvious advantages of the latter. My wife is going for the Ego, as she thinks it looks 'sexier'. lol
I'm not arguing...