I cannot count how many times I have seen this thread. But I want to see what you have to say on the matter . . . IMO, Ansem is by-far the best villain ever, followed by:

2. Sephiroth ( maybe Kefka)
3. Presidents Shinra ( notice the 's')
4. Riku

I want to see the full-potential of both characters realised. Meaning: Sephiroth's Solar Flare, Sin Harvest, etc. Ansem's Submit, Power over the Heartless, etc. I would also like to see: Motivations and beliefs expanded like Sephiroth's misanthropic views, and Ansem's search for godliness ( omnipotence and omniscience). As for whatever you consider their most redeaming qualities. It seemed that of the two, Sephiroth acted with more humanity. It is clear that what led to Sephiroth's mental breakdown was enevitable. He thought of himself as an abomination, but not to the degree of Cloud's ancestors. Ansem, on the other hand, began to desire knowledge and so he studied the Heart as well as Darkness and their connection. After choosing test-subjects, he experimented upon their Hearts, but to little avail. He confined their lifeless bodies beneath his castle. Once he realised what he had created, he began to spawn the Heartless artificially. His lust for power began with his embracement of the world's Energy Core. Take in each's power in the games they have been in. This does include CoM for Ansem, in which, he was, yes, rather difficult. And KH and VII for Sephiroth.

And for heavens sake, think of DiZ as well as Ansem, who looks like an amazing character. I have spoken to people who could not stand Ansem only for the fact that his initial battles were less than challenging. They all expect the same amazing comeback from DiZ as I do.