I wouldnt overdemonise the Black-White_Red. Yes, the Nazis used it for atime as a secondary flag (never as the single national flag, though - for a time, Germany did have two flags), but that was merely a cocnession to the conservative forces and scrapped as soon as the Nazis felt confident enough. Mainly, Black-White-Red is the flag of the Kaiserreich and German reactionary forces.
However, it indeed cannot compare to Black-Red-Gold. Its kinda ironic, because Black-Red-Gold IS accepted as the flag of German democracy by both sides, by the democrats themselves and the reactionaires sneering at democracy. That is why the Weimar reactionaries wanted to get rid of it, because it stood for a democratic republic, a state structure they abhorred. So, thus universally regogniced as flag of German democracy, there indeed was little alternative to it.