Olympus (tried both SC and MC versions) is hands down sharper than two copies of the Nikkor.
The Nikkor Has FAR better flare resistance - quite excellent actually, even on the copy I have with really bad cleaning marks in the coating.
The Nikkor makes very nice sun stars, The Oly makes average ones.
They both perform nicely up close, even though this isn't generally noted about the Oly.
The Oly is so frikken small, whereas the nikkor is.. not big but not overly small.
Which one is best depends wholly on your need for flare performance (if you shoot a lot of sunset landscapes with the sun in frame for example) and on how you like your hoshi (stars) for night shooting.
I prefer the Oly but even the MC one has slightly annoying flare.
Good luck!
Either is better than a zoom
(well maybe not the 14-24..)
