I have built or am building three of the bikes on your list. First i built the LCFS958, then the LCFS947 and now I am busy building the AM831.
When I am finished with the AM831 I will sell one of the three, two bikes is enough. But it will be a hard choice to make.
The LCFS958 is quick, a good climber, comfortable on lock rides, works well on descends and it feels very easy to handle in all cases.
The LCFS947 is a monster on descends, everything fells possible and not dangerous. On slow, technical, rocky climbs it conquers everything. Its a bike I prefer when i know its going to be more technical than fast rides.
The AM831 is 3 centimeters longer than the LCFS947 :-o What that mean when its time to ride it I don't know yet. Maybe its even more of the LCFS947 characteristics?