Neither. Manual simulation feels best for me. I can't always orgasm from oral (mental block) and strictly penetration doesn't get me off. I need some external friction. Groin rubbing, thrust bumping, fingers rubbing the clit.
A very large number of women can not get off from either strictly oral or penetrative sex. They need external stimuli to get off. That's normal. Much like there are men who can't get off from blow job's. Everyone is different.
We can't answer anything for your partner. Only she will know what she likes, and you should be asking her what she wants during the sexy times.