The paper that paper bags are made from after it gets roughed up slightly. Like, when you wrapped your school books with it and it's had like 6 months of use.

Vellum is the best but not vegan

I've always been a sucker for a good cotton linen paper.

Eggshell finish.

It has a nice tactile feel, but without the visual distraction of linens or laids.

If you haven’t tried stone paper, do yourself a favor and give it a whirl. Not only does it feel nice and smooth to the touch and writes like a dream but it’s also highly water resistant(I keep a notepad in my shirt pocket at work and if I moisture/sweat gets onto the open notebook it easily wipes off with minimal smearing), surprisingly tear resistant, and it has the added benefit of being tree-free (typically made with crushed limestone and a bit of recyclable HDPE resin for binding) bleach-free, acid-free, and uses minimal water in production.

100% cotton laid paper, preferably with a full deckle edge. The "laid" part is important, the wire mesh from the mould leaves a texture (like a watermark) you don't get with modern "wove" paper.

There's also quite a lot of handmade rag paper out there, most of which is nice. Just be careful of the ones with embedded flowers and stuff if you're using a laser printer, they can come out and stick to the rollers. (Also much of this is terrible to write on with a fountain pen, as it's not sized to stop the ink bleeding.)

velvet paper; It also feels deliciously buttery dragging a dry pastel over it or a very soft vine charcoal.