Maybe it's like picking a decade of music: clear limits in time and space, plenty of existing history, a feeling of affordability but also a sense of what's a collectible (scoped hierarchy), and being able to specialize among genre, artist, or any number of categories.

Picking a suitable "radar chart" of preferences, or surveying what's already there, is also part of the fun. Shopping for gear, too (turntables and headphones versus keyboards and serial consoles).

Why collect pre-JDK 8 docs? (Why not?)