Rabbi Shlomo ben Shimon Duran, the Rashbash (1400-1467)

"There is no doubt that living in Eretz Yisroel is a great mitzvah at all times, both during and after the time of the Temple, and my ancestor the Ramban (he was a sixth generation descendent of the Ramban) counted it as one of the mitzvos, as it says, 'You shall take possession of it and live in it,' and so is the opinion of my father the Rashbatz in his work Zohar Harakia. And even according to the Rambam who did not count it as a mitzvah, it is at least a Rabbinic mitzvah, besides the many other benefits of living there. However, during exile this is not a general mitzvah for all Jews, but on the contrary it is forbidden, as the Gemara says in the last chapter of Kesubos, that this is one of the oaths that the Holy One, blessed is He, made the Jews swear: that they not hurry the end and not go up as a wall. Go and see what happened to the children of Ephraim when they hurried the end! However, it is a mitzvah for any individual to go up and live there, but if there are considerations that prevent him he is not obligated." (Shailos Uteshuvos Rashbash, siman 2)