For armed security & protection, I would suggest a DA only sidearm. For regular uniformed carry, a sidearm with a ambi safety is good for weapon retention/officer safety. The new FNH FNS line(.40 & 9x19mm) is good.
I don't care for semi auto pistols with slide mounted Walther type safety controls. Frame mounted are better.
As a instructor, I'd encourage new class students to get DA only models or pistols like the FNS too.