Something funny happened to me when I listened to each led zeppelin album in order to first time.
At the beginning, the first album was great, i really thought that the led Zeppelin could not get a better album, but then I heard the second album and i loved it, to this moment, I felt it was just what I wanted to hear, the hard rock essence.
Then i heard the third album, and I did not like it at all, because I was not used to hearing those acoustic sounds coming from the Led Zeppelin, but we can't forget those great classics that this album gave us, like "Since I've been loving you" or "Immigrant song", then a
little disappointed, I heard the Led Zeppelin IV, and which made me the best album so far, and the same thing happened to me with the Houses of the holy, then Physical Graffity. In my opinion, the next three albums did not beat the Physical Graffity, but they were still good.
As conclusion all Led Zeppelin albums are good, and i can bet that there are people who prefer the first album, others the Led Zeppelin II, others the Houses or the holy, and do for each LZ album