Well, since we're talking about harem, I kinda liked Futakoi. Although the only girls that did display different personalities were the original twins (can't remember the name) and Sara/Shoujyu twins. The other twins were identical in each pair in terms of behaviour. But I found that the main character, while a bit flawed, was decent enough to SPOT an error when he makes one. Rin on the other hand is always oblivious to how his actions hurt people, along with AAALL his other "virtues". And even if I wasn't thrilled with Futakoi's ending, it was ok, a form of typical harem ending, but ok nonetheless. But Shuffle... bleh
The writers should be glad I liked Sia, Kaede and Primula enough to keep watching it