Which blocks are soft powered?

First let's clarify the distinction between hard/soft and strong/weak (the wiki conflates the two, confusing the matter):

All four lamps are active. The first is hard-powered (redstone signal can be pulled out), and strong-powered (powers redstone dust). The second one is hard-powered but weakly powered - power can be pulled out with a repeater, it can activate (soft-power) other blocks, but doesn't transmit power to redstone dust. The two right-side cases are both soft-powered (a.k.a. activated), one from strong, one from weak (but both hard-) powered cobblestone block. They act, they generate block updates and change block state, but they don't emit redstone power, whether strong or weak.

A torch, to the sides and below, emits strong, soft power - it can power redstone dust and repeaters, but only soft-powers (activates) solid blocks. Upwards, it emits standard strong hard power.

Answering the original question, the three lower blocks in the original image are all soft-powered (there's no real distinction between strong/weak here, they emit neither). The top block is hard, weakly powered (receives power directly from redstone dust, activates the torch.)