Which material do you feel offers the most intense stimulation without being overwhelming? I know that some silicones are firmer than other so please comment below if a certain silicone toy is firmer and closer to glass.
Yeah, I agree it's probably glass. (Although some silicones are plenty firm and rigid, like the Tantus Boss, for example.) And you really can apply as much pressure as you'd like with glass, so it can either be really, really intense, or a bit more subtle depending on how you use the toy.