Architecture buildings; ugly or beautiful?

LOVE THEM or loathe them, Brutalist buildings are architectural icons of modern cities. But many are crumbling. The question is, should we save these ‘heavy looking’ or ‘ugly’ concrete buildings that are often inefficient by modern building standards, or slay the grey goliaths to make room for more eco-friendly new builds. It's an emotive topic that gets people hot under the collar.