Ergonomics and Size

The P250 has the largest grip and feels great in my hand. I love this grip. This is also the largest of the 3 pistols. The FNP is an intermediate size and I can just place my hand completely on the grip. The Ruger is the smallest and absolutely needs the finger rest on the magazine. The SR9c is almost identical in size to a SIG P250 subcompact. SIG has the largest white dots on the sights. The Ruger has the smallest dots. 

SIG and FN

FN and Ruger

Ruger Sights

SIG Sights

Conclusions