Which component do you think is more likely to use force against the American People?

If the law is followed, then the National Guard. Different set of rules. Posse Comitatus applies to the Army, not the other services. However, regulations within those services essentially implement the same thing. Although force against US citizens is considered an illegal order, it gets much murkier when it comes to National Guard and Coast Guard. The latter has various law enforcement aspects. So legally, the actives and reserves are on the far side of "NO", the Guard depending on their state regulations which vary near the center, and the Coast Guard probably more towards "Yes" but under statue for only certain things. A legal expert can provide a sharper answer but the notion that Posse Comitatus is an all covering blanket isn't correct. Legality aside, our military culture hates the idea, especially when we see all the countries that use their military to suppress the population. We typically don't join up to act like a banana republic.

None would ever do it. We might "fight" among ourselves but that's a "family" squabble not anything else. If I HAD to pick a branch, it'd be the one who has the most annoying mandatory training, all done in PowerPoint, and couldn't leave until the commander stops running his gums about the importance of having a reserved parking spot in front of the company area. To get out of all that, you could pick almost any branch except the Coast Guard.

IMO, may God forbid it to ever happen, I think it would be the National Guard.