Question: Can you suggest a scholarly/critical edition of RaMBaM's Mishneh Torah?
Answer: The Shabse Frenkel edition of the Mishneh Torah [Nyu Yorḳ : Ḳehilat Bene Yosef, 1975-], is complete and has extensive textual variants listed on the side of the page and, especially, in the back of the volume. The RaMBaM Meduyak [Maʻaleh Adumim : Hotsaʾa Shilat, 2004 -], edited by Yitshak Shilat, is devoted to producing a critical “meduyak” edition of the Mishneh Torah. I do not believe it has been completed yet. However, a good number of volumes have been done already and it may be completed soon.