Why does Luden's give the most AP out of the Lost Chapter upgrades?
Mages generally have two options for their first item: Rod of Ages, or a Lost Chapter upgrade. Battlemages like Aurelion Sol, and Swain usually go from RoA because the scaling health and mana is very valuable for sustained damage.
Burst mages and artillery mages usually build a Lost Chapter upgrade because they need the mana sustain from Lost Chapter's passive and the CDR. Burst mages want to chunk people with a combo, and artillery mages want to poke, and Luden's Echo is the best option for both of those things. The extra 100+ damage from the Luden's proc makes both of these types of damage more powerful, and give them better waveclear to boot.
However, Luden's also gives the most AP out of any of the Lost Chapter upgrades. It just seems like the best option in almost every case. Besides a Glacial Augment cheese strat or a specific case like Ryze that scales of the mana from Tear, Luden's dominates the build path for burst and artillery mages.
Wouldn't it be better if the three Lost Chapter upgrades were each situationally equivalent?