I've got my first ever messy session coming soon, and I am wanting to have a slime that looks similar (doesn't have to be exactly perfect!) to the picture provided.
On messy supplies there's MS, Natrasol or methylcelluouse. I was thinking Xtra Thick would be the best one, but of the three mentioned, which is closest? Ideally I don't want the slime to be very drippy or liquidy.
I would go with natrosol, by far the easiest to mix and gives good coverage. I'd make it thicker than you think you need it as you can always add a bit of water to thin it down and it does improve if left to thicken for twenty minutes or so.
2nd Natrosol. I'd recommend the thick stuff. The regular is really runny and transparent. You can probably go with the x-tra thick, but like the person above me said you can just use less water on the thick and adjust. Good luck.
you're unlikely to get the exact effect in the reference picture from those three. Natrosol and mehtylcellulose tend to get more 'blobby' as you get thicker, which won't produce the stringy effect in the ref. From MessySupplies, the best match would be their Vivi-Slime. The lite will be more liquidy, the "Xtreme" will be thicker and less liquidy (similar to a PVA glue slime).
You can probably also make a mix yourself using K-Lube and HEC/Natrosol, which would allow you to control the thickness and color more precisely, I use the recipe here: https://gooeypony.com/gunge-hec/