Of the realistic toys I've owned, six are silicone (three VixSkins, two Super Softs, and one O2), one is elastomer, and one was a jelly toy that I never even used.
The VixSkins are my favorite - the outer layer is very soft and forgiving, while the inner core helps makes them easy to control and direct. My favorite is the Tex (it's my favorite toy in the world!), though the Mustang felt slightly more like a real cock, though they both come close.
The O2 Mark is pretty nice, too. It's not as soft as the VixSkins, but it's still a great toy.