I am not agreeing or disagreeing about whether Diana is suitable or not, but what i want to point out is that being pulled over for drunk driving, cussing out the cops, holding a baby over a balcony, taking drugs, beating up the neighbors, etc., does not make you an unsuitable parent/guardian, per se. There are several people who do these things (expect the balcony one) who are excellent parents/guardians. The behavior becomes a danger to the child if the parent neglects the child while doing these activities or places the child in a situation where the child can be harmed. Some even said that Michael placed his child in a situation where he could be harmed, but look at what a wonderful parent/guardian Michael was.
Now if we see that Diana's children were mistreated, neglected, emotionally harmed by her drunkenness and sharp tongue then we can say that she is not a suitable parent/guardian.
I also hope that we know that some children love their parents deeply, even though they know that their parents were not the best parents in the world.
I think the important thing about a guardian for Paris at this point, is not what we or society think a guardian should be, but what does the guardian have that the child NEEDS. Does Katherine have what Paris needs? Does TJ have what Paris needs? I think if they don't, then the judge should come up with a plan to make the guardians satisfy the child's needs. We can't look for perfect people, since Michael was not perfect and none of us is. Imperfect people make good parents/guardians all the time. The thing is they have to recognize where they are weak, and do something about it to help their children.