Doggystyle + his work on The Chronic, and Murder Was the Case. Obviously Doggfather was a step down but it was decent.
Most rappers batting averages go down significantly if they keep releasing albums for decades: KRS, LL, those last two Rakim albums, Cube, PE, etc.
Only 80s/90s rapper who really maintained that batting average for his whole career that I can think of is Scarface.
Frankly, I don’t even consider LL, Rakim, KRS’s late career stuff when considering their GOAT status. To me once you reach a certain point in your career, everything that comes after is treated like bonus points that can only help your grade but not hurt it.