I want to preface my answer by saying it's about a fantasy world. In a real world scenario, people should feel responsible to stop the fights if it's safe for them and there is a possibility of someone getting seriously injured. For me, the excitment of catfight comes from two factors: 1. The woman's body in different sexy poses. 2. The primality of the fight. So, I lean towards the more violent fights. But there are two caveats.
1- The fight should be fair and consensual from start to finish. There should be two women going against one another one-on-one without any weapons or sucker punches or hurting an already beaten enemy. Any sexual humiliation should be a means to win the fight and not a goal in itself.
2- The other coveat is that the violence of the action should not take away from the sexiness of women's bodies. So I don't like anything like blood, broken bones eye gouging or things of that nature. And of course no fatality. To me, the reason that women fight doesn't matter at all.
If I want to make a tiers for myself, these would be tiers:
1. Match instead of fight. These are fights with strict rules same as MMA, boxing wrestling etc.. These are not fights. These are jobs/hobbies that are dangerous. So any violent present in these matches is like an injury doing package delivery/hiking etc.. I think this is the most boring category that souldn't really be called catfight.
2. The fights were the enemies fight without any specific rules but there are safeguards against the fight getting too violent. For example, people around to stop the fight.
3. Same as 2 but the fight is allowed to finish. The fight stops when either of the girls decide it's over. It could be due to one side surrendering or being neutralized and therefore losing the ability to consent. Note that by the enemy getting neutralized I don't mean when someone gets on top or you are 80% sure that the winner is determined. I mean a knockout, being tied up, or being too badly hurt.
4. Anything goes fight where only the winner decides when to end the fight and might continue after the fight is won without needing the loser's consent. This type of fight contains measures that are not aimed at neutralizing the opponent's ability to hurt you but also torturing them.
5. Fights to death without the possibility of backing out mid fight.
For me the sweetspot is 2 to 3 in my own tier list. Where there is enough violence and primality and goes for long enough that you can determine one of the combatants is better than the other. Also, it is not so bad that you would feel guilt about watching the fight and not stopping it. Frankly, I would say 3 is the best when it comes to seeing the fight. However, it's in a position where it starts to raise some moral questions about not stopping the fight. Ultimately, I think 3 is morally okay. Because both fighters know what they got themselves into and both agree to fight to the finish. But it still feels wrong for some reason. Please let me know your opinion about if it's okay to watch a tier 3 fight and not stop the fight.
My first brushes with catfights were when I was a teenager by movies/TV shows and video games like Mortal Combat. Each time I would like it a lot and it would linger in my mind for a few days. However, the most formative experience was a fight that I witnessed more than 15 years ago. The fight was completely fair and consensual. Both girls very attractive in revealing clothes and both (especially the loser) got exposed. The quality of action was very good with both girls giving it their all. And it ended very decisively with a knockout (the girl I was cheering for won). The reason for fight was also very trivial. I think all of my choices come from that specific fight. You can read about it here:
https://www.freecatfights.com/forums/index.php?topic=116712.0