I played Light sided for both classes, and I think the Warrior is better suited for a Light sided story than the Inquisitor. The Warrior starts off as a member of the nobility, while the Inquisitor starts off as a slave. So the warrior has seen the best that the Empire has to offer, while the Inquisitor has seen the worst. Now the Inquisitor story works if you want to go Light side, but if I had to choose just one to be the "good guy" I'd go with the Warrior.
And keep in mind that the warrior's apprentice will have a different personality and abilities based on if you're going Light or Dark sided with her. No other class has a companion that changes to that degree.
Not only that, but the Warrior does not have to fight in order to be recognised as a Sith. He already is respected and seen as a noble. So the Warrior is one that is born to lead out of the box, which basically meant "leading by example" from level 10 onwards for me. E.g. before asking the military to do throw away lives, you spearhead an asault. Also, people are more willing to fight for you if they respect you and are able to look up to you. That means mercy and compassion goes a long way in the long run.
The Inquisitor however gets pushed around a lot. On both my Sorcerer and my Assassin I felt I needed to push back hard in order to show people that even a former slave can be a force to be reckoned with. Only later on, when the story transcends ppower struggles, I found myself getting more lenient and political in my decisions.
My Juggernaut reached 50 being Light II, both Sorcerer and Assassin were neutral (the Sorcerer was close to Light I however) when finishing their class stories.
I agree completely that the SW story makes a lot of sense played as LS.