I would say that my fav cardstock to use with my copics is the Neenah paper- it just takes up the color so well and doesn't get blotchy, which I do get sometimes with my SU cardstock.
As for images- oh the world is at your command! I love to use the Magnolia's, Whiff of Joy, Sarah Kay and SU (larger flowers/picture scenes). I have a bunch of different images/types that i have on my blog-stop over and take a look if you would like!
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