When finger picking open chords one is supposed to do Thumb - bass string (root string), Index 3rd string, ring second string etc.

The bass string used should be the "root" of the note. ie If playing an E chord one should pluck the E string, if playing a D then the D string.

My question is:... If one is using barre chords to ,say, play a A# chord (Based on E shape on E string) then which bass string should be plucked? The A or the E String???