Dr. Christopher used Eleuthero (Siberian Ginseng...not a true ginseng) and Gotu Kola for adrenal adaptogens. Aswagandha (I assume) wasn't a known/popular herb in the US at the time of Dr. Christopher's work
Please read the two articles above to increase your knowledge of the various adaptogens, what defines an adaptogen and how each work...and then you'll have a MUCH better idea of which will be best for you.
The most important thing when dealing with adrenal distress is to eliminate the CAUSE of the adrenal distress...which is invariably STRESS!
We're a society of pill-popping-fix-us-up-when-something-is-wrong people, so please be sure to be just as focused on your research for ways to reduce what CAUSED your adrenal issues, as ways to treat & heal the damage that's been done.
My recommendation? Dr. Christopher's Adrenal Formula...our contains DOUBLE the qty of herbs for balancing adrenals (eleuthero, gotu kola & mullein), plus it contains other herbs for assisting the heart & circulation (generally ALWAYS at issue with the adrenals).
You can take up to 3 tablespoons of Ashwagandha root powder daily - so if you['re not up to the 3T, you might want to try taking more of that.