My choice was titanium, which I used to make ours. It is (IMHO) among the finest of all materials for the job.
Titanium should also work great for forced amputation in the case of a broken finger I suppose...
Every metal mentioned has someone talking about losing a finger. Do you work for a silicone ring company?
For me, before I touch a lathe or mill, the ring goes in my left back pocket. Every time.
To wax poetic for a little while, Ti is lightweight, strong, warms quickly to the touch but isn't cold in winter, resists abrasion, doesn't irritate, and is almost immune to corrosion. Its strength allows a lower-profile ring without collapse, too. When making rings for our wedding, I could have used any material under the sun; titanium was our choice.
A material need not be rare to have significance, so it is with love.
Titanium / Tungsten / Silver are for people who want an inexpensive ring.