Walls first for me but then I am good with lines and a square..........plus if you are doing 'brick' bond then not all the joints will need to be accurate as they will not meet.
Usually the main feature wall first then the floor to flow off that ie bond through. Making the walls and floor bond is a major plus in the setting out in my opinion.
Usually walls first for me unless I'm lining floor and walls up. If I'm doing a full bathroom install and the client isn't having a tiled bath panel but one purchased for their bath then I do the floor first as it can be a nightmare otherwise.