I have internships lined up in the 3 of these firms. Which one should I focus on to try getting a PPO?

None, go for Trilegal.

If your focus is on work environment and culture.

KCO > JSA > AZB

What about in terms of them being upfront about giving PPOs?

But they don't have slots empty at any given time. ;-;

You made this post to boast about your internships huh.... it's literally worth nothing if you don't actually put in the grind hours

lol i wish and thanks will the later part in mind when I feel like slacking there.

At the outset, try everything everywhere, unless the slots are clashing or you're certain that you're reaching a breaking point of exhaustion.

But if you're specifically targetting a PPO and have these options, I would advise you to avoid JSA on the basis of several reasons, better explained at https://www.legallyindia.com/convos/topic/256776-which-big-7-law-firm-is-the-most-reluctant-one-to-give-a-ppo

Between KCo & AZB, if you have to choose, then let it be on the basis of your college profile and how much time you have left. KCo has a one-internship policy but is extremely selective in terms of your work review — not a great idea to bet on this one opportunity.

On the other hand, unless you're from a T1 NLU, AZB has a general callback policy, and they've been giving out a number of interviews lately.

So, if you have the time to do a callback or are from a T1 college, focus on AZB. Otherwise, focus on KCo.

In any case, my advice remains that you should focus on everything you can when it comes to potential PPOs.

Okay the situation stands like, I just got done with the semester exams of 4th year.

You are in which year?

getting done with my 4th year.