For pure precision work is the SSA-E best. If shooting in a situation, where nerves are tight, SSA.
I bought a SSA-E for my AR15 patrol style rifle. The trigger pull is too light for this rifle (for my taste). This is my fun rifle, shooting prone, kneeling, sitting, standing, lay back, broke back mountain..... The SSA-E gives not enough resistance, some shots came too eraly.
So I put the SSA-E into my precision dedicated AR10. There it is perfect!
I bought a SSA for my patrol rifle. Perfect! Crisp, not too much or too light trigger pull.
YMMV ;o)