Originally posted by
I think it depends what you're going for.
Silicone will bend and flex, where glass and metal toys don't. You can get more pronounced temperature play with glass and metal.
In addition, any textures on a glass toy will feel much more pronounced than it would on a silicone toy, and toys of hard materials feel bigger than toys of soft materials.
It's all about preference. Some people swear up and down that glass feels the best, while others will say silicone is the material to go for - the same holds true for any material, really.