A Glock M21. End all be all.
AS much as I am a very big fan of this ultra reliable, soft shooting, accurate big bore, it does not conceal nearly as easily as a G19, or single stack 1911.
I did executive protection years ago for the governor, and due to the size of the issued G21, and related printing of such under a suit coat, I opted to carry my Kimber 1911, as it definitely concealed easier in an IWB rig from Sparks.
Where the G21/G21SF really shines, though is not often mentioned, is as an outdoorsman's sidearm. Especially when running heavy for caliber, cast bullets. Essentially running +P to .45 Super loads. With a basic load, including one in the chamber, and a reload with a +4 extension, that is 31 rounds of hard hitting .45 caliber projectiles.