Parkavenue, i think you are trying to coerce some of the members into 'which watch is more valuable'. I think you are just out here asking questions for your own intersts or trying to make the public think this watch is more valuable than the other.
You even said 'Certainly it is true that the World Time Watches and the Ten Day Watches of Patek Philippe are simple watches to make. After all they made 3,000 ten day watches, and probably could have made even more of them'.
It seems like you are forgetting about the movement of the watch, the size of the company and the many other factors which results in the production. How can one person simply comment like how you did. If patek has the ability to employ BETTER SKILLED watchmakers and in LARGER QUANTITIES, how can you something that? Is it a CRIME TO BE GOOD AT SOMETHING? Maybe we can even say Lange watchmakers are inefficient and lazy slobs who can't get something done right the 1st time around. (i do not meant that in real life, and sorry to the watchmakersof lange, you guys are awsome too!). Again, this is like a comparison between APPLES AND ORANGES.
I don't care if a 5131 is easier to make. It would be useful for a person who have to travel around the world, or have associates around the world! Who cares if it's more difficult to make? IF YOU WANT TO ASK SUCH A QUESTION, might as well put it as patek 5131 agains a lang timezone. You can compare the movement and details. That would be such a better way to compare!
What kind of talk is it to just comment something like that. We migh as well ask about a patek sky-moon tourbullion against a lange 1. For all you know, 5970 movement could be the easiest as they buy it from Lemina, which they case it or tweak it slightly (might be wrong here), compared to a calatrava which they do u from scratch?! Isn't that the best way to satisfy you in terms of 'difficult to make'?!
You should seriously think before you ask such questions.