Well, I have to disagree with some parts, but yeah it's weird how trends change. I'm no expert, and I can't claim to have been in the industry for years, but I bought a hookah off of caravan trading. Lasted 2 weeks, then rusted out. So I replaced it with an MZ. I've had it two months now and it still works great. Hopefully I can say that in a year or two lol, so we'll see.
I've never owned a KM or Mya so I can't compare the two to MZ. I've never seen any threads complaining about any of the three, really. It seems to be mostly personal preference/wallet.