Xscape has better albums, and better tracks. What does SWV have for Understanding, Who Can I Run To, Tonight... Anything and So Into You doesn't stand up to those. Weak may compete. My 2 favorite SWV tracks are Use Your Heart, and Human Nature remix of Right Here, but those don't hit the same as the Xscape tracks.
Xscape has the MC Lyte track - whatever soundtrack that was on...and they can both use Freedom. There was a time when people said Taj couldn't sing. That was never said about Xscape. I think it will be lopsided.