Quoted from mof:
To anyone new to Priest, here are the stone cold hard facts:
Their "Black album" was British Steel, when they moved from slower medium pace heavy rock to mainstream-pop-metal to sell records.
Their first 4 albums are the best, and the rest is formulaic and very uninspiring. (which I found a way to enjoy back in the day, where we had VERY few choices)
Painkiller is Priest at their absolute worst. They are not built for speed. They are a vocal band, and there's no room for vocal expression at high velocities, and they have a top-10 all time singer... Listen to him on Sad Wings... incredible singing and expression.
Go back and listen to:
1. Rocka Rolla (warmest production of a heavy rock album I know)
2. Sad Wings (best production of a metal album EVER)
3. Sin after Sin
4. Stained Class
And you can cold stop there.
What you had with Priest is an evolution of a heavy blues band into a heavier metal band. You can follow the transition through all the albums. RockaRolla is very blues based ... and every album heads more "metal" from there.
You gotta remember that when RR came out in 1974, "metal" as we know it didn't really exist. You had Sabbath, Purple and Zeppelin (who refuse to be labeled metal at all) and a handful of other bands, all firmly rooted in the British blues boom of the late 60s.
You could argue that the evolution of Priest from 1974-1980 actually defined "heavy metal" as we know it today, not only musically but also visually with the adoption of the S&M leather and studs gear in the late 70s.
I would slightly disagree on the British Steel "black album" point ... while it does have United, Breaking the law and living after midnight, it also has Rapid Fire which you could argue is the prototype speed metal song.
And it was followed by JPs landmark albums, Screaming for Vengance and Defenders of the Faith.
(Don't mention Turbo)
As far as later Priest (Painkiller onwards, and the Ripper albums) obviously Scott Travis had a huge influence on the band, as the whole musical style changed. Again, further evolution ... if they were still making Rocka Rolla in 2017 then they'd be playing a local pub in Birmingham.