You probably won't like this one, but on two machines, I have a combination of:
1. Plain simple micro switches.
2. "Factory" enclosed micro switches.
3. Slotted Optical switches.
4. Hall effect.
I find all of them to be accurate and repeatable within the limits of my machines.
IF your going to machine ferrous materials, forget Hall effect.
IF your going to do a lot of "dusty" materials, I would forget optical (unless totally enclosed such as those made by Hoss or IHC)
IF your going to use coolant, unless they can be shielded I would not use open micro switches again unless they are in a sealed enclosure.
My two cents.