Not all silicone is created the same. You can get some silicones that feel velvety soft and silky, like Lelo silicone and others that feel very 'grippy', like Tantus' shiny silicone. There are also many other varieties in between, such as Vixen Creations (which feels very skin-like) and even Tantus O2 or more matte silicone.
In other words, silicone can feel very different, depending on the type/brand you go for, which is good news. You get to choose how it feels, by choosing a brand/type that most closely matches your desires.
So, considering that you can, kinda, choose the feel and the firmness (Silicone comes in a variety of firmnesses too) why should you choose it over TPE/TPR/Latex etc?
Well, silicone is a very stable material. Being so stable, with tight bonds, it is virtually non-porous. TPE, jelly etc is porous. Why does this matter? Well, it helps reduce/remove the risk of transferring infection. Most medical grade silicone can be sterilised with 10% bleach solution and boiling water, so it is basically easier to keep clean.
It isn't just bacteria that can hide inside pores, but other things, like odour, dyes and even mould. You may have experienced, or know somone who has experienced a toy getting black spots, or starting to hold an odour, or having soaked up stains from bags or packaging etc. Being virtually non-porous, silicone has a much higher resistancy to these things and with proper care, can last a lifetime.
Unstable materials (like jelly) tend to break down/deteriorate over time. They also tend to smell very chemically because they are leeching oils or chemicals used to make them (Some toys even leave an oily stain on the surface it is stored) Silicone doesn't break down and is odourless.
So the benefits to choosing medical grade silicone toys?
They can last a lifetime. They are odourless. They are body safe (Don't leech chemicals that can irritate the delicate mucuous membranes of the vagina/rectum). They can often be sterlised. They are virtually non-porous (So they are much less likely to soak up odours, chemicals, bacteria, mould or dyes) and all round fabulous. :D