I often opt for the emergency rows on the 800 and 900. (Not the 700 though.

Two things for me:

A) I've often found that if Im in EC and arrive after boarding starts that the overhead bin space is limited. Being sat in the emergency exit row means you usually get protected bin space.

B) i think every time I've been upgraded intra Europe is when I've been sat in the emergency row... but that might just be chance... and to be honest the data points are fairly limited