Yeah, I'd say Bo1 got the most attention, just because there was so many new things (weapons, perks etc)
Nacht, Verruckt and Shi no numa are all re-jigged campaign maps, whereas der-reise is a totally new map.
So my list would be:
As for bo2, I think buried had the most work put into it. With the giant, witches, permaperks, timebomb etc, lots of stuff was thought about. Even the design of the map, everything is different. On Origins, lots of the map is the same.