Wyll is neutral, not good. He cares very much about people thinking that he is a hero, but there are several opportunities in the game to witness how this is a facade.
I agree that this is a facade, but at the same time we don't get to see much of will beside this facade and his reputation.
I'm not sure if vengeance put him out of the good range. If you look at anomen quest , seeking vengeance made him broke his oath, but it was because he broke the human law. Does it applies to a vile gobelins, that is per say a enemy of humanity that any paladin would slaughter? I mean, Paladin DO smite evil foes when they have to, without looking back. This is why I'm hesitating for Will, its a big ambiguous.
At the same time, he is kinda linked to a demon, which no Loyal good character would do. So maybe he is Loyal neutral.
True neutral character don't really care about anything (like druid) and can take either side, so I doubt he is that.
