Taking the types Messy Supplies sells, which do you find has the most arousing feeling for you guys against your skin?

I have only tried the MS gunge and methylcellulose from them. I couldn't notice a huge difference in feel between them, except that with the extra thick grade of both, the MS gunge came out thicker.
I'd be curious to hear if anyone has played with the Extreme version of Vivi-Slime, as I've only seen the stock pictures of it.

I've always used natrosol. I've bought from different suppliers in the past, but for me Messy Supplies is the best. It coats well and it feels amazing, smooth and wonderfully slimy.

I've used the Vivi-slime lite. It doesn't feel different to natrosol, it just looks different in terms of the stretchy effect. It was however a bastard to mix. Even with a hand-held food blender it came out lumpy which might have altered the feeling of it, and I tried a couple of techniques of mixing it.

smooth but thick cake batter

Having only really used cake batter and oatmeal, when I learned about Xantham Gum I was blown away with how it felt.

I gather that messy supplies will ship internationally, so I do fully intend to order some for a session with a buddy soon, as I have heard that has the most amazing feeling.

Does anyone know what the difference between MS>>Gunge and Natrosol is?

The data sheets for both are listed as "Hydroxyethylcellulose".

Natrosol is actually the trademarked name I believe. It's the same stuff in effect.
https://en.wikipedia.org/wiki/Hydroxyethyl_cellulose

We love xanthan gum. It feels great, can be easely mixed into different thicknesses, easy to clean, odourless and dirt cheap.