i say Sue, cuz not only can she do all the things alreday mentioned she can also reduce the size of her force bubbles to microscopic sizes until they just blink out of existence.
i am not 100 on the science behind this but i think the reason magneto is even able to create forcefileds of his own is becuase he either alters, or vibrates the natural electrical and metallic molecules that float freely in the air. if this is so, since the natural order of matter is
atom
molecule
macromolecule
organelle
cell
tissue
organ
organ system
idk, maybe she could create one that starts at the size of an atom, or even of subatomic size just in case Mags messes with atoms instead, she could easily slip it between the interstitial spaces of the molecules or atoms, and form it around his helmet. from there, she would have the choice of suffocating him, or just decreasing the size once again crushing his skull in the process.
at first i was considering that magneto would have more experience but when sue made the transition from IG to IW, she realized the full extent of all her abilites, especially after she was mind controlled by psychoman