Should I wear eyeliner or eyeshadow?

Okay, so my mom HATES me wearing makeup so I am only allowed to use a little bit. I'm planning to ask my mom to let me wear more makeup for the next school year. I don't wanna ask for too much or I know I will get a no, so I will ask in time. Besides all of the skin stuff (foundation, concealer, etc.) I only wear mascara. I'm not sure if I should ask to wear eyeshadow or eyeliner. If it was eyeshadow it would be neutral-ish (no bright pinks, purples,etc.) and if it was eyeliner it would be light. I have light blue-ish green-ish eyes which everybody says are my best features. I am not sure which one would enhance it more. Help?? Thankss :D