Not for that reason (IIRC, they can tell whether someone is at their peak, so that would not work,) but because one was a Brown and the other was PRACTICALLY a Brown, and both spent most of their lives in secluded research. If investigating channeling, they would have cause to use the Power, but otherwise there is little need or motive to channel ones way through rooms full of thick musty old tomes, and the few exceptions that required MASSIVE channeling were probably quite rare. And reaching ones full strength is like any other strength: Those who rarely or never use it never develop it. Forced to pick one or the other rather than both, I would say Adeleas; even if Vandene soon became a Brown in all but name, she was RAISED Green, and the Battle Ajah definitely has cause to channel early and often.

Technically, it depends on how we are to understand "old school" AS, but it would be pretty shocking if one of the AoL AS were below full strength, because that is pretty much just Forsaken, and it is hard to see how anyone could reach that brutally competitive level, much less stay alive there, unless full strength. So it seems like it must be a "new old school Aes Sedai," so likely someone with lots of gray who nonetheless always lacked not only the need to channel but most of the DESIRE practically synonymous with AS. If anyone fits the description of someone too often preoccupied and distracted to even remember their thirst to channel, it is a Brown, and I believe Adeleas was pretty much the oldest Brown. Thus she strikes me as the best candidate.