It blows away RK and even GB on the scorecard for gore and has a more interesting story
RK was NOT bad and GB was definitely NOT bad.... its just that SDK is THAT good.
SDK has character development which is even superior to RK and GB (Unfortunately this is only evident in the manga)
SDK has a bigger cast of interesting characters (Even in the anime and more so in the manga)
SDK Character design is superlative..... and so is the animation.... (Seen in both anime and manga)
SDK follows Japanese History in a way which is more up close and personal than RK which makes it even more gripping..... (Both anime and manga)
We get to meet Yukimura Sanada, Nobunaga Oda, Hidetada Tokugawa, Ieayasu Tokugawa and other important figures from Japanese History (Both anime and Manga)
I am rambling now.....