Congrats on your ZM, great camera! You will enjoy it.
If you are OK with f/2.8, the Zeiss Biogon 35 2.8 is fantastic, small and good value for money. My Brother-in-law (one of the best photographers I ever met) has the 35 2.8 as well as the C-Sonnar 50 1.5. I have the Biogon 35 2.0 and the Planar 50 2.0. We love to exchange lenses but apart from the difference in max aperture, we never saw much difference between the 35 2.8 and 2.0. The 2.0, by the way, is a great companion to the Planar, exact same size, and very similar rendering. Love that Planar (I much prefer it to the C-Sonnar, but that's just me)
Bottom line, it all depends on your budget - a Zeiss 35 will set you back around $600 for f/2.8, a couple hundred more for f/2. If you want to spend that money, go for Zeiss, If you want faster for the same money, go with Voigtlander. I think you cannot go wrong either way. The 35mm Distagon 1.4 is overkill in my opinion, it's huge, more than twice as expensive, and blocks a big chunk of the viewfinder - although surely a fine lens. I had a look at it in a store, mounted it on my camera and immediately decided for the 35 2.0 (which I got used for a very good price). If I want a lens that big I can as well shoot an SLR.
As a side note and for what it's worth, the only M-mount lenses which I found not to be compatible with the ZM are 1) the Leica 28-35-50 Tri Elmar (it mounts but the viewfinder frames do not switch according to the selected focal length) and 2) the Leica summicron dual range, which cannot focus at infinity (risk of damaging the shutter) and whose goggles do not fit the camera. There might be others. Hope this helps