Should I join IIM Indore as a fresher or give a second CAT attempt to convert IIM ABC?

The decision depends on many factors because CAT is a highly competitive exam that requires dedicated preparation. If you think you can manage your CAT preparation along with your job, you can give yourself a second chance while getting familiar with some of the courses that are going to come up in the PGP program. You should use this time to upskill yourself in your field of interest.

ABC is also a bigger brand than IIM Indore, but ultimately, it's the skills that matter in the long run. The PGP program will be rigorous, and you should be mentally prepared to handle it. Additionally, there are no guarantees in life or in CAT, and the selection process involves an element of luck, with the interview round being extremely subjective. I suggest having an honest discussion with yourself and weighing all your options before making a decision.