Over the course of several decades the Master of Architecture has become an increasingly expected degree, to the extent that many BArch holders eventually will pursue an MArch as well.
I think this is due to the ever evolving complexity of architecture into tangents and niches that are pertinent to the practice today: for example, sustainability, digital design, community involvement, government regulation, innovative materials and technologies. A deep and broad background in the art history of building design is also important as architecture is a combination of technology, art and commerce.
Along with considering the different curriculums (and different time and money investments) I would also consider the different cultures and environments of the parent institutions. Neither is better than the other, but the composition of the overall student bodies will lead to different undergraduate experiences.