I personally prefer Kay's translations over the others. For all the different translations I've read, Kay is the best one. Besides, why shouldn't they receive donations for their work??
It's just a moral thing.
Let's say you are a translator too and have been translating a manhwa for several months, making it popular with the constant releases (I know the manhwa isn't really made by translators, but people wouldn't know about these manhwas if not for translators).
So yeah, at that point, the manhwa is basically your child since you spent so much time on it... then here comes some new guy, randomly joins in from chapter.. let's say 200, and have been sharing around his donation links to basically feed off of the manhwa's popularity, which, once again, you made popular over several months or even years.
Now, you probably can't imagine this and I can't really come up with a better comparison, but don't you think it's quite rude as hell? In my eyes, it's basically just greediness and morally wrong.
As for your preference; Kay admitted already he is using AI and other machine translators to translate. I know MTL can be certainly good if you actually take your time proofreading and making sure the translation is good for each chapter, but at that point, the 3 other translations are good enough too, no? They are most likely using the same MTL too, just maybe not proofread well.