I also love my rigid stainless steel Pure Plug. It is easy to insert, it has the perfect shape to stimulate my G-spot via the anal/vaginal wall, and it warms up quickly and retains temperature so much better than all the other materials.
I don't have one single material preference. Each has their pros and cons. Many good choices as long as the material is body safe.
My single favorite plug is a wooden plug, the Nob Essence Romp. It just fits me perfectly!
I have more silicone plugs than any other material. So many sizes and shapes available and what's not to love about silicone.
I also have an ASSorttment of glass and stainless steel plugs. Smooth, solid and weighty. Very nice.
I also have a few hard plastic plugs and prostate toys that I am pleased with.
I prefer steel and glass. I like them with a more bulbous shape rather than tapered. Glass and steel give such a slick feeling and it gives my partner awesome stimulation during intercourse while he's thrusting when I'm wearing one.
Silicone is my fave by far. I love that it moves with my body and is comfortable for long term wear. I also love that it's completely sterilizable. I do like the glass Sexy Spade medium, though. I don't know how it would fair for long term wear though.