Kluson MG33C

Very nice and smooth. Why would you pay more? It is easily the cheapest way to upgrade a cheap-ish guitar and really enhance the tuning stability.

Don't be afraid of drilling new holes. Just buy a size 2 drill bit at the DIY store (size could be hard to find), mark the bit with tape so that it can't go to deep...
and then just "dry fit" the tuner, put a dot where the hole must come, and go on and drill it.

My cort Z22 whent from 'okay' tuning to super stabile. I even wonder what it would be like if I also change the nut to a bone or Tusq model.

Don't bother buying more expensive tuners... Okay, it's not a premium brand, but it works exactly as good als the originals who are 3x as expensive