I have the Oasis 3 and my husband has the PW5 (because I gave him it for Christmas

).
I would say the PW5 has the edge, but they are nigh indistinguishable.
I have set them to the same page, same font and taken a picture so you can see.
They are at the same settings, Bookerly size 4, no bold, light and orange light both 16, in the second photo I changed the orange to 18 on the Oasis so they looked the same in real life.