A Behance dot grid notebook was with me at every meeting until it ran out of pages. I recently replaced it with a Whitelines notebook, which I like even better.
Those whitelines notebooks are a great hack on the traditional lined paper. I like the structure of lined paper but dislike how the drawn lines on the papers lines make it hard to see. Great find!
Konigi graph paper looks decent for wireframing: http://konigi.com/tools/overview
As do Whiteline books (you can buy them off Amazon): http://www.whitelines.se/en/
I personally use and recommend Muji recycled ring notebooks. They're relatively cheap and excellent for quick sketches/journaling: http://www.muji.us/store/stationery/note/recycled-paper-note...
For me, anything that'll let me get my ideas on paper as quickly and effortlessly as possible is the way to go. As long as the notebook doesn't get in the way, it's perfect.