I am always on the hunt for good paper. Bad paper makes me a bad writer, especially when using dip nibs, as those sharp points will catch on upstrokes which is extremely frustrating.
At the moment, the Clairefontaine Triomphe is one of my favorites for practice. The images above were written with a Hunt 56 dip nib, which is particularly sharp and prone to catching on the paper. But on this sheet, it glides along smooth as butter and allows me to concentrate on the actual writing.
If you look closely on the first image, you can see the imprints of whatever I wrote on the other side of the page using the same nib. I press down very hard with these nibs to get a large shade, and sometimes the pressure bleeds the paper which leaves a mark on the other side. Not with this paper, as you see, it only leaves a raised surface but does not bleed through. Very impressive!