British Steel rules. They had an album or two later on that I didn't like that much where they started to get a little top 40ish for my tastes, but then they sort of redeemed themself with Painkiller.
If you want a good mix (and you actually still by CD's) check out their double CD MetalWorks 73 - 93. It's got a good mix of songs, although not all the tracks I would have chose.
I've never listened to anything after Halford left. I'll have to hit Kazaa.
