@Dew Spinner I have 3 different chapter 15 cities. Main Halls are the same level (level 33) in all of them. 1 of my cities has a level 6 Tome of Secrets and a 2nd one of my cities has a level 6 Endless Excavation. So this is pretty much a direct, equal comparison of EE vs ToS at chapter 15.
In my Arendyll city EE gives me 246,000 supplies every 24 hours. And it has the trivial secondary effect of giving me a few extra relics when I complete a map province.
In my Winyandor city, ToS gives me 492,000 supplies every time I scout. My scout time is currently about 36 hours. When you adjust this to a 24 hour period, supply production is about 327,000 in a day. Which is about 81,000 better than my equal level EE in Arrendyll. And my ToS gives me 2 knowledge points every day, which is a way better secondary benefit than the relics from EE.
Based on these numbers, I would say that as late in the game as Ch 15, ToS is a pretty good AW.