My wife and I are big fans of Vixskin. It's the most realistic silicone material we've seen. Being silicone, it's non-porous, which means it can be fully sanitized, doesn't pick up odors as badly as porous realistic materials (e.g.
UR3) and can be shared without having to use condoms (assuming, of course, that it's properly cleaned).
As far as the realism, some Vixskin toys (Mustang and Johnny, to name our two faves) are quite a lot like the real thing, in appearance and feel. Other toys (like Raquel) feel realistic but don't look realistic. Vixskin is a "dual-density&quo t; silicone. It has a firm inner core and a softer outer layer. That makes it rigid like an erection, but soft (like skin) to the touch and flexible.
They're also very durable. Our Vixskin toys are all still just like new, despite our giving them some VERY passionate use. The only real drawback is that you can't use silicone lubes with Vixskin, because that would damage the material badly (but this is true with almost all silicone toys).
We've also tried Tantus's O2, which is another realistic silicone material, but we like Vixskin better because, in our opinion, it's more like the real thing and that's what we like.