Definitely Daggerfall. It was the only one that broke the "OMG must save the world from ultimate evil!" cliche that I am BORED AS HELL OF.
And there was no good vs. evil. Even your stereotypical evil (orcs and Mannimarco) had motives that were neither good or evil. Hell, I'll just say it outright those two, along with the Underking, were the most qualified of being the 'good guys.' Mannimarco just wanted to be a god to give Arkay the finger, nothing of much, if any, consequence (sure, grandma may be used for necromatic experiments, but it's nothing but a husk of dead flesh at this point). He didn't want to rule the world, burn it, enslave it, etc. The orsimer were trying to FINALLY be accepted after years of attempted genocide against them. They didn't want to kill everyone, burn the world, enslaves anyone, etc, just have their own territory and be recognized as citizens of the empire. For the Underking, he just wanted his soul back and be put to rest. Everyone else just wanted power to rule that area, and the blades were just following orders from Uriel to stop the damn fighting between these damned city states.
One thing they all have in common is that they all turn out the same way every time you play them. :yawn:
Except for Daggerfall, unless you believe that since all ending have it where someone gets stompy bot counts.