I am surprised the series being so ignored, since it's Tanaka Yoshiki's works (he is the author of Legend of the Galactic Heroes ). But again, I realize it can very much lack elements makes an anime popular such as moe...
Spoiler for Ryoko:
Very crazy but smart woman. Ryoko is the perfect and unbeatable queen (this is not some first impression or background description will be changed by stories but what happens in the stories). While very quick in actions, she is not slow in considerations, and she is always capable of completely destroy whoever stands on her way (except Yukiko perhaps).
Social status, power, and money are nothing in front of her, or more precisely, she is more eager to destroy those with social status, power, and money, and this is not because she loves justice but, in my opinion, is just because beating up rather tough opponents make things more exciting than bully weaklings.
The lines she likes most are WINNER IS THE KING, LAWS EXIST ONLY FOR MY SAKE or something similar.