Welcome to footantic! In this thread we use @clubelo's API data (based on the Elo rating system) to compile the best European clubs per decade, on average. This doesn't look at peaks but rather how consistently great the clubs were during that decade.
The 1970s were dominated by Liverpool, followed by Borussia Mönchengladbach and hot on their heels Ajax Amsterdam.
The best team of the 1980s was Bayern Munich, closely followed by Liverpool with Real Madrid rounding up the top three.
The first decade of the new millenium was dominated by Manchester United, followed by the Spanish giants Barcelona and Real Madrid.