I wasn't really old enough to see the attitude Era play out, but from what I've watched, I likely would have gone with WWE from 1996-1998 and 2000-2001. 1999 was just such a shit year all around.
I personally think '99 was WCW's worst year so I still would have been pretty on board with WWF then.
I'm Canadian.....all we got was the WWF.