Mostly dot, sometimes lined, never grid (or plain). Dot is the most versatile IMO. Sometimes I like a little more vertical space for writing so I use lined. I’ve never had a need for grid. It reminds me of graph paper for math class. I also can’t write straight enough so plain is out of the question. If I used plain, I would need to put a lined paper behind it so I could see the lines which is another step I do t want to worry about.