between moto atrix and iphone 4, i'll go with iphone 4 simply you'll get a better experience using it. between moto atrix and SE Arc..the choice is simple..Arc rules. the real hard choice comes when you put Galaxy SII and Iphone 4, i.e. Andriod vs iOS.
To me the phone is damn good with its blazing speed and crisp screen unless you dont mess with its built in stable android version by upgrading to latest os version. Its dual core tegra 2 processor (as i mainly prefer playing high quality games and videos on the phone along with somewhat browsing on it) with Moto blur and bio metric features have really impressed me. A lot more customizable than any iphone out of the box without jail brakes or rooting. The new 4g from at&t comes with ginger board 2.3 so no updating yet. Still in my opinion moto needs to have more widgets...thats one of thing i will say it does need to improve such as MARKET. I have been using it for a while but thats one of my few observations if you use this for business and world runs on stock market its an essential app to have. Well even i can download it from MARKET but i want built in widget. However Kudos to Atrix!
All the new phones lately have been on par. They have all the FB, Tweet stuff but when it comes down to apps, the iPhone capped the market. I dont like Apple but the phone and the millions of apps are just too fun to have. Anything you cn think of, theres an app for it.