There are a couple of factors to consider when choosing a ruling size for journaling: the size of your handwriting, and how much writing you want to put on each page.
If you have larger handwriting or do calligraphy, you will want a larger ruling on your pages. The MyEssential lined notebooks have 8mm ruling, allowing you to write larger to show all the details of your handwriting. The MyEssential notebooks also have numbered pages and index pages to organize your journaling easily.
If you prefer a smaller ruling, the Habana notebooks have 5.5mm ruling and come in pocket and large sizes. The firm covers have a leather-like material that comes in 6 colors.