I might be biased since I work for ASUS but I still haven't seen any proof of a widespread battery drain issue that some users like to talk about. You will have better battery life with ZenFone 6 than most other phone if they are all used in the exact same way.
If Sreekiran believe that he has a battery drain issue, then there's a simple test he can perform to find out if there is a hardware issue or if there is some app that's draining the battery. In this test, you simply needs to put your phone in flight mode without charging when you go to sleep. The battery loss shouldn't be more than 1% per hour of sleep. If you have lost more than that, then we can log your phone to find out why.