Which distro to use for learning linux(from job perspective). Which distro is used by most software companies? I was wondering about whether to go for RHEL or Ubuntu or any other. What would be the best choice?
I really don't think it matters nearly as much as how comfortable you are with a Linux environment and the tools available (and knowing about the tools available, and how to use them).
I have been using Unix/Linux since the early 1990s, and I still come across stuff I didn't know about. One of the major strengths of this OS is the wide range of tools available and the flexibility of accomplishing tasks by sometimes combining them.
Once you are comfortable in a Linux environment, the adjustment to a given distribution will be minor. You'd probably notice changing your default shell more than changing the distribution :)