The Midrash Project at the Schechter Institute of Jewish Studies is publishing a series of books on midrash, including critical editions of at least eight midrashim. The series is edited by Profs. David Golinkin and Shamma Friedman. Each critical edition presents the midrash based on the best manuscript, and includes selected variant readings, reference to parallel sources in Rabbinic literature, and a critical commentary.
These are the books from the series that have been published so far:
Midrash Shmuel, edited by Prof. Berachyahu Lifshitz, 2009.