Walther PPS
I have a PPS in 40, wish I had gotten the 9.
It is nice and thin, and grip length can be short for concealment, or longer for range use.
With the larger capacity mag's, even in 40 it is easy to maintain a good grip at the range.
I have put several thousand rounds through it.
It has functioned flawlessly with every round I have used!
Every thing from low power "work up" hand loads, to high power factory loads have functioned properly.
It can be made safe and unusable by pulling off the back-strap of the grip.
This de-cocks the striker without allowing it to hit a chambered round.
The striker will not stay cocked until the back-strap is replaced.
The only down side I have seen is the thin grip on my 40 digs into the web on my hand, and after a few hundred rounds actually caused a friction blister.
I don't think this would be as big a problem in 9mm, and that is the main reason I wish I had chosen the 9 over the 40.
If older models were allowed, I would say a Star Super B, but then you are into a full size.