Detachments: Since unit with ASF are "even striking before enemies that have charged," the ASF strikes first.
ASF vs. ASL: I am not sure, if this was addressed in 6th. Contrary to ASL, ASF was not a generic BRB special rule in 6th. The rules for Swordmasters for instance specified that they struck in Initiative order, despite having a GW.
In 7th ASF was a generic BRB special rule, which bypassed even ASL.
Q. When two models with the Always Strikes First (ASF) rule are in combat, and one is equipped with a Great Weapon, does the model equipped with the Great Weapon strike last? For example, if a High Elf model with an Initiative value of 6 and equipped with a Great Weapon is fighting against an enemy model with the ASF rule, an Initiative of4, and a hand weapon, who strikes first in the combat?
A. When two models with the ASF rule are fighting, they will strike in descending Initiative order, rolling a dice in case of same Initiative. All other factors, such as charging, great weapons, etc., are ignored, because they have already been bypassed by the ASF rule.