Hello,

Both your certificate are acceptable though your state board certificate will have higher preference than the one you obtained for NIOS. If you were fail in your state board examination then you gave NIOS exam so you will have to you mention your board NIOS but if you were not fail and then you gave NIOS exam for the improvement of your marks  so you can mention your any one of the board it maybe state board or NIOS board.

Hope it helps.