if i may go off on something of a tangent so much of what made the show work(or not work)was the chemistry between the actors involved.
for example in this viewers opinion jonathan frid had it IN SPADES with lara parker and grayson hall. yet despite josette being barnabas' "great love" i never found him to have it with kathryn leigh scott. on the same note he didn't have it with donna wadrey as roxanne either.
but again he had it with alexandra,nancy and joan.
scott for her part had nice chemistry going not with frid but with joel crothers(obviously),david ford and john karlen. for this reason a maggie/willie romance seems to be a fan favorite even though that never quite came to fruition on the show itself even though it was suggested. those two actors played so well off each other. apart from everthing else i never bought for a second the maggie/nicholas pairing because there was zero chemistry with astredo.
the nice interplay between joan and alexandra would also play a part in the fan's favoring of the liz-as-vicki's-mother theory as much as anything else.
for what it's worth despite their being partnered up as the show's marketable "antiheros" in later years i never cared for scenes between frid and david selby either.