I have approximately 400 dollars (could make it a bit more) and i want to buy an android mobile phone. Two things are very important for me:
1- Battery power: how long a battery can last for
2- Camera power: I already have a Nokia 6220 Classic with a carl zeis 5 MP camera; the photo's i take with this camera are great (compared to what i need the pics for) and are much better than my friend's 8 MP Xperia X-10.
You should check Samsung Fit or Samsung Galaxy S or Galaxy S II, Picture quality plus battery life on samsung phones are awesome. If you are so much worried about battery issue, Samsung rockkks. You will get benefited with lightweight device and Amoled display.
Also you may consider LG phones. They are nice shaped and quite handy style designs.