But on the note of the original question... I always play Light Side. Why? Well, I'm one of the few who actually adore long conversations, I like finishing all the quests, talking to all the people, finding out every little tidbit of information I can get my greedy little hands on. But apart from that personal geek gain, playing LS is so much more fulfilling. I'm not really enjoying myself when I run around screaming "Aaarrgh leave me alone you worms I'll crush you with my awesome DS powers grrrwwaaarrrgghhhh I hate you all POWER!!!!!..." You get the picture.
And I don't find myself at any loss regarding powers. I'm quite happy with Stasis, Destroy Droid, Force Wave, and old faithful Heal. Sure, when I don't know what to choose, I can always take Storm or Kill and suffer the little penalty, but in battles I usually Stasify the opponents, hack and slash away, and have a darksider electrocute them with Storm all the while. Wow. Putting it like this, I am cruel.
I play LS because I love all the little people. And deep down I strongly believe in happy endings.
But as to the whole Sith Philosophy vs. Jedi Philosophy vs. Grey Side Philosophy discussion... I guess I'd see it from Jolee's point of view. Grrwaarggh Kill Kill Kill darksiders are annoying, and so are preachy lightsider Jedi. Both the Codes are a bit doubtful. I'd go light side to the end (when you reach the glow and little stars, probably the Jedi equivalent of an aureola
Since I haven't finished KotOR II yet, I don't know much about the 'questions' some of you have mentioned, but I remember the way my faith was shaken back when I faced Bastila on the Rakatan Temple Summit. And Malak's departing words hit me deeply. Kudos to KotOR, it's really not as plastic and black-and-white as some other SW franchise expansions, or indeed the original movies.