Bands that released their best album late in their career

Candlemass albums with Lowe are their best IMO. Yes I know that's blasphemous.
Europe's later output (especially Bag of Bones) is miles ahead of the old stuff as well.

Accept? Sure, Balls and Breaker I hold as their very best, but Blood of the Nations comes in 3rd for me, not bad for a band that had a solid first decade of high quality output, and a five year period (´81-´86) of classics in a row. Stalingrad and, though to a slightly lesser degree, Blind Rage are solid as well.

Marshall law. Their album razorhead is awesome.

Kyuss for sure, though their career was brief, their third album "Sky Valley" is light years ahead of it's predecessors. Wretch was a band starting to get their feet wet, Blues for the Red Sun, was a definite step further in establishing their sound, but Sky Valley was one of the greatest music albums EVER made. It deserves all the accolades it receives and then some. Still criminally underated even within the metal community.
Believe it or not, Kittie comes to mind. While their first album, SPIT was a nu-metal down-tuned mess, the girls actually learned their instruments and can be safely considered power metal on their last three albums, which aren't that bad, especially Funeral for Yesterday.

I think Accept is crushing it now in a way they never did, even if their earlier stuff was good.

Horrorscope is good, but I love Ironbound. It's just nonstop amazing.

Completely agree with Pretty Maids, they just keep getting better.

Jag Panzer, as amazing as they've always been, is as good as ever.

Ultimatum - I think Into the Pit is hands-down their best (Lex Metalis is awesome, but of course covers). They just seemed to be hitting their tightest and heaviest and most melodic on Into the Pit.