The best advice one can give to any watercolour artist about what paper to use is to try different brands, weights and textures and then decide which best suits your style.
Some paper absorbs the paints much more readily than others; if the paint sits on the surface the colour is much more easily lifted out. So, if you like to reveal highlights by dampening areas and removing paint this latter type might be ideal for you. If, on the other hand, you prefer to put colour down in layers or glazes, one on top of the other, a paper which absorbs the paint would be more appropriate.
If I want textured effects I will use a Rough textured paper. If I want a lot of detail or a more fluid look I am as likely to use a smooth textured hot pressed surface.
I almost invariably buy my paper in large sheets (30”x22”) and cut it down to the size I want. This is much more flexible (and economical) than buying pads or blocks.
This month’s painting, ‘Eynesford’, had a fair amount of wet-in-wet work, particularly in the water, so I used a 200lb Not paper.