World at War was great, but as good as it was its obviously the first run and you could see how they worked and improved it as they went. Even with a lot of people not liking Shangrila, I feel like Black Ops just got the most out of it. Kept a story going, kept it fun, the maps were made for both the mobile and defensive gamers, they added in mini bosses and toyed with the guns more, it just worked, especially once ascension came along and they environment really started coming into its own.
to all questions, there lies but one simple answer: mooka.
As far as map progression, WAW hands down. Each new map that came out improved upon the last one by a good bit, and peaked with arguably one of the most beloved maps to date. Der Riese has something for everyone. You can camp, you can kite, you can use traps, the map is just the right size. There are so many ways possible to play on it and do well. Everything after is hit or miss, with some really good maps and some really bad ones, but they have yet to capture what they pulled off with that map, at least speaking for myself.
The PAP is still one of the greatest additions to zombies, and instead of coming up with something on par with it they keep focusing on easter egg map design. They were on the right track with Tranzit, but all the playable areas are too isolated from each other and kill the flow of the map. Die Rise is a fantastic map with many ways to play and a huge step in the right direction. The wait time on elevators is my only gripe, they can really drag an already lengthy game out to the point of boredom. Everything else about Die Rise I love though, it might make my top 3 of all time. The remaining DLC has it's work cut out to compete with Die Rise.
Wow! You're so hardcore I'll bet you play Tic Tac Toe as a full contact sport! -HappyHappyJoyJoy