80's 90's undisputedly the best, by mid 2000's started the DECLINE of Dancehall to were it is today. It has changed so much today you can't even call it Dancehall because there's nothing Dancehall about it.
1993-1994 then 1997-1999, these two eras has the most "immortal" dancehall tracks (riddims & singles). I've been playing music since the 90's and have been researching this for a while now.
end of 70s and begining of the 80s : you can hear rocksteady and rub a dub Most prolific era for music creation in reggae