I had my fingers crossed that someone would come out with a 357 Sig version of their single stack CC pistols at SHOT this year, but ended up disappointed. My money will go to the first one that brings 357 Sig to the table. I would be fall over happy with any of these.
Springfield XDs 357 Sig
Smith and Wesson Shield 357 Sig
Beretta Nano 357 Sig
Walther PPS 357 Sig
While I wait, the G27 with 357 Sig conversion barrel works for practice.