I enjoyed Sephiroth and Kefka from the FF series. Their character was so fully developed it was almos like you could feel the energy in the fight between your characters and the boss, the tension, the struggle, etc. Especially when you go through the game in a speed rush using no spells, summons, etc. only items and physical attacks (unless the bosses needed spells, then they were very weak) and also trying to do the lowest levle runs (like level 34 or 46, i get the numbers mixed up, cant remember my lowest level to beat seph, i think it was 46 when I had my stats maxed from fighting the things in the submarine that drop all the +stat items when you morph them).