What smartphone should I buy for $500?

In my other post, you'll see that I have a budget of $800. Some guy suggested me the OnePlus One, which $300 for 16GB. So do you have any suggestions for a $500 phone? Here are some of my requirements:

1. Android 4.4 KitKat Doesn't need to be Google Android

2. Higher than 10 MP Rear Camera

3. 2 MP or higher front facing camera

4. Quad-core 2 GHz or faster

5. 5 inch display or bigger


7. 2,200 mAh battery or higher

8. 2 GB RAM or higher

9. $500 budget (I already thought of buying 2 phones. The other is the OnePlus One)

Thanks :)