Keep in mind in the inkjet world, "matte" refers to actual honest matte papers, not that crazy N-surface nonsense chemical RC printers consider to be matte.
Epson includes instructions with everything, but it's really easy: If it's glossy, photo black. If it's matte, matte black. There is nothing in between in the Epson line. If you have to ask yourself "Is this a matte paper?" the answer's no.
Or you can just print on everything with photo black depending on your personal style and goals. The blacks are considerably less dense on matte paper printing that way, but for some images it's not really an issue.