As others have pointed out, the Companions quest line starts with you beating up a woman. LoL, way to go DragonBorn!
The other thing that quest line has you do is slaughter the Silver Hand group. The people in that group are pretty despicable, with their torture and dismemberment of werewolves and suspected werewolves, but would a 'good' person participate in their slaughter, just because they oppose the Companions?
Umm, no. The Companions questline does NOT start that way. My first "quest" was to fight with Vilkas (or maybe Farkas - one of the Companions, anyway) to prove my skills. Once I did that, I was given the quest to go find the artifact, as I mentioned.
At no time did the Companions ask me to go beat anyone up. Someone else mentioned that the TG questline starts that way - maybe it does, I don't know, haven't done that. But it sure isn't the Companions that sends you to beat someone up - not early, anyway.
And if they do ask you to do something you don't like, guess what - don't do it. Just stop the questline. I don't see a problem there.
As to the SilverHand issue - I can understand this being more grey. However, personally, again, I think a good character would want to stop people who were torturing and killing others for sport. The fact that those others are werewolves - some at least - may cloud the issue, but overall, being asked to stop people from harming innocents is something a good person would do, IMO.
There's a difference between playing a "good" character and playing a character who will never kill. The first is an interesting RP choice, IMO. The second makes me wonder how on earth you could possibly get through this game at all. I did see a thread where someone mentioned they had companions or summons do all the killing, while their character just healed, distracted, etc. I suppose that would work.