Which Conrad Goetz chinrest should I buy for violin or viola?

For violin, the Stuber-style chinrest listed here is boxwood with titanium screws. For viola, the Kaufmann-style option is boxwood with Gold Hill screws, while the Slim-style option is ebony.

Those descriptions help narrow the choice, but they cannot tell you which will feel best under your jaw. If possible, try the relevant shapes on your own instrument and check that you can hold it comfortably without clenching.

Don't choose on wood or screw material alone. Instrument compatibility, chinrest shape and a secure fit matter more than appearance; a violin shop can help check the fit before you commit.