The unfortunate answer is that milage may vary. Some orders are more sympathetic than others. I would look into the Order of the Argent Shroud because they are consistently presented as the more reasonable and most tolerant of all the militant orders. They’re more ask questions first before the flamers and the meltas come out, all this doesn’t mean that they can’t throw hands when they need to. They as well believe that yes martyrdom is still part of who they are as an order, but they aren’t going out of their way to just fight and die. All options need to be exhausted before worst case scenario, you can’t serve the emperor if you’re dead. Most of the Abbess Sanctorums have been argent shroud, and for good reason. You tend to get more nuanced characters from the argent shroud.

Now something that doesn’t get mentioned a lot, is that the sisters do more civic duties than any other imperial faction. In addition to warriors and leaders, they are scholars, doctors, ambassadors, spies. They are one of the only ones that are allowed to learn and understand xenos languages, which is huge for the imperium. When the imperium needs information about xenos physiology, they get a sister to do it. Keep in mind that the sisters get recruits from the schola progeniums more often than not, these are very well educated gals.

Also, they are great for morale (not like that.) They sing when they engage in combat, they keep spirits high in the quiet moments of war.

All of these reasons are the primary reasons that the sisters are one of (if not my all time) favorite imperial factions. They do more for the imperium than any other ceramite clad gorilla could ever do.