No debate in this... Flash in every sense the most important... Booster as is place but look at all the Flashes in DC history and their importance in all timelines and events.
Theres eveen a "flashfobia"... flashpoint, crisis, jay garrick, bart allen, the importance of kid flash as wally west in teen titans, the lightning saga and the legio of 3 worlds... Flash is part of the multiverse continuum That Bbooster Gold helps to protect.