Finally I was able to solve the issue but worth mentioning that what didn't worked to solve this login stuck issue
- All sort of reset like PRAM etc
- Boot in Safe mode
- Reinstalling OS from recovery mode or internet recovery mode
- Deleting user's Library preferences or LaunchAgents
As I mentioned in my original problem, I waited for 10.12.5 to get launched. I reinstalled 10.12.5 but guess what. The problem still as it is. I was not able to go past login screen. Needless to say frustration was small word to describe my situation.
Since I had my guest account working, so I changed the password for my admin account. After this, something strange happened. I was able to past login screen, black flash screen and I was back to login screen. I changed my password back to original password and I get stuck at login screen with wheel revolving.
I created a new standard user and I was able to login using the standard user.
Now one thing was clear to me (just intuition to be honest) that my problem has nothing to do macOS otherwise Apple must have fixed the bug in 10.12.4. So with this intuition I generalise my problem and started hunting on web around the login problems people have faced after OSX/macOS upgrade on their existing admin account. For weeks I didn't get any fruitful outcome.
When I was almost going to give up and was planning to format 😟 my hard disk and clean install 10.12.5 , I came across this thread Fix for El Capitan stuck at login.
Without wasting a second I tried the solution this gentlemen had proposed.
WOW WOW WOW. 😎 😎
I was back into my MacBook with same login. All my content intact with macOS at 10.12.5.
Another good thing happened during hunting. I learned back all those forgotten UNIX command like ls, cd sudo, rm, rmdir 🙂 🙂