Sil a gel is the most disgusting thing I have ever smelt. It's like being suffocated with a pool raft. NEVER AGAIN
Sil a gel is a brand name for an additive that is anti-bacterial in nature; it is not a base material. The base of these toys are TPR or UR3 and any rubber/petroleum based product is going to have an odor to it.
I am not as picky about material. If it feels good I'll take whatever precautions needed to keep it sanitary and safe to use. I have yet to try a jelly toy however seeing other people responses makes me think those look like a headache.
I absolutely hate jelly, but I also try to stay away from most other porous toys. I also try to stay away from UR3 and other "lifelike skin" materials because they're so high-maintenance. Generally if it's not silicone, glass, or metal, I'm a little wary about buying it.
I've tried all of these materials (except for wood, which I would like to try) - and the only one I wouldn't ever get again is jelly. It's so gross how it smells and how oily it feels. The other materials I don't like are rubber and TPR, but I could deal with them if it was a really awesome toy.