It's Only Rock 'n Roll has the three really good/great songs and a few more that I guess are good enough, but the bottom half of it could not be less inspired. I don't think that they released anything weaker outside of the '80s. Undercover is the It's Only Rock 'n Roll of the '80s and the two after it are even worse. The later albums my have weaker top-3s, but on the balance they're more enjoyable.
Holy cow, I knew that people didn't expect Martin to finish the series before he dies, but I did not realize that he hadn't published a new one in the entire time that I've known who he is.