Tony always said he considered himself a "soldier" and the battles they did was essentially criminal against criminal. To a certain extent, I can go with this "reasoning." However, I think there are a few people he killed that was less in defense of or in favor of the family, and him just killing for the sake of his personal benefit. The two that come to mind are:

1. Chris Moltisanti - It seemed like Tony killed him just to get rid of him. Chris at the time was doing nothing against the family or Tony.
2. Ralphie Ciferreto - Yeah, they had their differences, but Ralphie was nothing but an earner and while Tony did not like him, Ralphie's death in my mind wasn't justified in the context of the mob life.

Any others?