As a DM, I do more "running" than "playing" but my choice here might surprise some of you. However, I promote the worship of Ehlonna in Greyhawk and my homebrew, Toneeze Wurld (aka Hackmaster Association Garweeze Wurld #161!). With my home group (the Guardians of the Polar Bear, made up of family), my kids mostly play halfling and elves and I tend to recommend NG alignment (although I do allow anything, sometimes with disastrous results!). Elhonna just speaks to me, mostly as a Roman Catholic and a lover of Professor Tolkien's Middle Earth. I am reminded in some ways of both the Blessed Virgin and Elbereth Gilthoniel from Middle Earth.
Now my choice as a player is probably equally surprising. As I mentioned earlier this week, I like to play clerics and paladins and cavaliers, usually of a Lawful Good bent. Now admittedly the choices there are a little. . . .vanilla. St. Cuthbert, Pholtus, Hieroenous, maybe even Pelor. In the 3.5 Greyhawk Gazeteer, paladins of Rao are described like Jedi: wearing robes, carrying out diplomacy, only pulling there swords as a last last resort or to protect the weak, etc. No, my favorite deity as a player has to be Hextor, Herald of Hell and Lord of Tyranny. There's something darkly attractive about the bad guys and especially the Lawful Evil ones. They have a plan; they're not mindless, psychopathic killers. Heck, they usually have a rudimentary code of honor, even if it does benefit the strong. This even worms its way into my DMing; for instance, in my City-State of the Invincible Overlord, the Hellbridge Temple is dedicated to Hextor, not the Baleful Eye of Morg. Hextor also takes up a Title as Guardian of the Gates to Hell. But that is another story.
So, there you have it: one goddess of Light balanced by one god of Darkness. Until next time, gentle readers, say your prayers and sleep tight!