I own three excellent guns in this segment, and I it would be very hard for me to single one out from a precision standpoint.
Beretta Storm SC is a DA/SA, chubby but holds 13 rds.
Steyr S9, holds 10 rds. Ergonomic, accurate.
Walther PPS has different magazines, I favor the 7 rds for it's size.
All of then have been absolutely reliable, and I recommend them all. For ease of concealment, the Walther wins. Otherwise, a draw amongst them.