In my opinion Metallica have only released one bad album and that is St. Anger. It is just IMO a bad record even if it wasn’t a Metallica record.
IMO, Kill 'Em All is a good album but missing the depth of later work. While it is musically important, as an album judged on its own merits, it’s just okay. Not the strongest debut.
They peak IMO from Ride the Lightning through Metallica.
Load & Reload would’ve made an amazing single album. Problem was it was too much too soon. Change of sound, change of style, cutting their hair, even changing the logo. Way too many changes to do all at once with your first record in five years. The material on each as such isn’t given a fair listen by most without already existing bad taste.
Death Magnetic was a safe return to form.
Hardwired is their best record since 91. If Hardwired had been released in 94 as a sort of transition to Load, I think their career would’ve been much different.