In general the bigger the footprint the more inherently stable they are, all things else being equal. So ranking in terms of stabiliy ht3>ht2s>SCST....Another factor is height, they are all roughly the same, then last cg. The HT3 with the larger woofer lower help stability. The sound scape series would also be stable. I don't know how the 8,10 or 12 would rank relative to the ht3, but probably better than the ht2.
Given all that my SCST could take a hell of a wack. Fortunately I have them about a foot from the wall and they aren't near any traffic pattern, and no kids, and the cat hasn't seemed interested in them at all. (He's declawed, they are not scratching posts!!)