Which marcas have changed the most from olden times? Which are the most consistent?

[Vitola Corleone]

Inspired by a comment from @NSXCIGAR in the recent R&J thread: 

For those of us that are relatively new to the CC game, which marcas are most consistent with the character that made them famous in the last century? Which have changed the most and how? Does anyone know why these changes occurred -- is it new strains of tobacco, cultivation practices, or something else? 

By "olden times" let's say before the disaster of 1998-2001, or whenever the experienced palates have noticed a significant shift. 

Caveat that this all assumes there is an essential character to most marcas, setting aside the debate on whether there is any such thing (I think there is for many of them). 

[Edicion]

Great topic.