Lenovo a369i. As of now, I do not see a better phone at this price. Do not even look at those brands which offer a lot of high end features at low price, they all will fail to deliver.
If you can extend your budget to 7k, Moto E is a much better choice.
Have a look at Asus Zenfone 4 also, it is priced at 6k and has a good set of features. Although I did not use this phone, I expect this to be a decent one being from Asus.