I personally using Asus Zenfone 5 from july 2015. Asus zenfone 5 is a good phone to buy before lenovo k3 or k4 launched.
Now in 2016 go for k3 note or k4 note .
Asus zenfone has 2gb ram which is good but battery drain fast as compare to k3 note.
If you want to buy asus zenfone 5 go for it.