I've owned all three, and I will give you my impressions of the three first, then suggest one more alternative.
The SIG SP2022 is a good pistol...certainly for the price...and I am a fan of DA/SA action with a decocker. However, this pistol is (IMO) a little big for CCW. That varies by the person and how you dress, of course...and how you intend to carry (IWB, OWB, or off body.)
The Ruger SR9c is a good pistol too, and does come with a thumb safety. I just couldn't get really comfortable with the grip, though...it just seemed too small with the flat base plate, and not quite right with the extended base plate on the magazine. Of course, with the 17 round full size mag, it was too big for CCW. One thing I really did like about this pistol: it is very easy to remove the striker and clean out the channel; also, removing the mag disconnect was extremely easy.
The M&P9c is my favorite of the 3 pistols mentioned. It is just right in the hand (IMO) and carries well. It had a good capacity (12 rounds) in the standard mags, and the FS mags will give you 17 rounds. Mine doesn't have a mag disconnect or a safety...which I prefer.
Now, for an additional consideration: take a look at a Ruger LC9. It is smaller than any of the three mentioned above, has a 7 + 1 capacity, it is hammer fired, and comes with a mag disconnect and a thumb safety. (I don't care for the mag disconnect, but I can live with it.) It is really good for CCW, and I can actually carry it in my pocket...some say it is too big for them to do that, but I can manage it just fine (one advantage to wearing big boy pants!

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