If they actually have to live together, build a life and family together, make a living etc... It has to be Min. She is not a lunatic (see Aviendha), she is not a pampered snot coddled from her youth (see Elayne). She is the closest thing to a sane female that Jordan has in these books.

There are two rules a man should obey when contemplating marriage (other than that he should be physically attracted to and in love with the woman):

1. Don't marry crazy.
2. Don't marry high maintenance.

Incidentally, both Elayne and Aviendha fail at least one of the two criteria.

That said, I would pick Aviendha for a less permanent relationship. She is hot and interesting.