Thanks for the input. Its good to hear from someone with a lot of edits. I'll take that in to consideration.

It doesn't outright say one way is correct over the other but I take the "One feature, one OSM element" good practice principle (https://wiki.openstreetmap.org/wiki/One_feature,_one_OSM_element) to be if there is one occupant of a building, the tags should be added to the building. If multiple business occupy a building then it gets points for each occupant.

This explanation is also what I base that on: https://help.openstreetmap.org/questions/22962/should-i-use-pois-or-areas-to-identify-shops

Once you start looking at buildings, this can sometimes get a little grey. I think of buildings with a business below and unnamed apartments above. It gets a little odd to map.

Thanks again for the input :-)