If you are looking for an unlocked phone then your best choices under $400 are Xperia SL, LG Nexus 4, Galaxy S II and iphone 4. Iphone 4 is not an android device and Galaxy S II is old and the specs are not as good as Xperia SL and LG Nexus 4. Nexus 4 is way faster and it has newer OS and bigger screen but with nexus 4 you get just 13GB of storage. You can insert a memory card in none of Nexus 4 or Xperia SL so the file transfer becomes a little hard. Xperia SL's internal memory is 32GB. The battery on Nexus 4 also doesn't last for a long time Xperia SL's battery life is not much better either it has just slight advantage over Nexus 4. When performing heavy tasks on Nexus 4 back of the device gets warm. Xperia SL has higher resolution camera. Apart from memory, battery life and camera Nexus 4 is the best but if you care a lot about the memory and battery life then Xperia SL. http://www.gsmarena.com/sony_xperia_sl-4894.php http://www.gsmarena.com/lg_nexus_4_e960-5048.php
everyone suggestion is good... but you should go to android... coz this the latest and cheap technology in these days.....
yeah I am agree with this to use android..... android is best for the latest world... I am using this and this is great experience for me..
Almost everyone's suggestion are good. But don't go for Samsung bcoz now-a-days samsung devices have lots of complaints... So i prefer you going for Micromax and Sony.
The Nexus 5 is great value for money, it performs like all of the other flagship phones and then some. It has a great selection of applications as it is android and a brilliant set of features, it is definitely worth a look!