I found one of the most powerful of the poems to be the one called "Reconciliation":
When you are standing at your hero's grave,
Or near some homeless village where he died,
Remember, through your heart's rekindling pride,
The German soldiers who were loyal and brave.
Men fought like brutes; and hideous things were done:
And you have nourished hatred, harsh and blind.
But in that Golgotha perhaps you'll find
The mothers of the men who killed your son.
I find it interesting, the contrast between the rabid anti-German feeling that seemed to be so common among the civilian population during WW1 (here in Australia too by all accounts) and the fellow-feeling felt by many of the British and allied soldiers for their German counterparts. They were all suffering together in a hell created by their respective leaders.
I have also been considering why I find the poems of Wilfred Owen more moving than those of Siegfried Sassoon. I think it is a combination of knowing that he did not survive, and also the use of his poems in Benjamin Britten's "War Requiem". This is an incredibly powerful work written in the 1960s for the new Coventry Cathedral, combining some of the poems of Owen with words from the requiem mass.
I think all these poems should be required reading for all politicians itching to send more of their citizens off to war.