It depends on what I'm shooting, in what circumstance, and with what camera.
With my view camera and BW film - I use my spot meter 90% of the time.
With MF cameras (usually color neg and slides) I use incident meters 90% of the time.
With 35mm rangefinders (mine are meterless) I use a handheld reflective meter about 60% of the time, and switch it to incident for the other 40% - unless I'm in sunny 16 mode.
This is out in the field anyway. In the studio I use all three, to read different things, and generate exposure based off of all of them.
FWIW - I find that for me, the Zone system really works best if you can adjust development for each individual exposure (+/-N dev). Hard to do with rollfilm, so I don't worry about it as long as my shadows and highlights are within the range I want them for a given film and expected processing.