9mm
After I read where you have decided to purchase a Beretta I'm just adding my 2 cents worth for the heck of it.
I purchased one of the P1's (Walther) from Impact Arms last year and it is a top quality firearm. Slick as a baby's butt, accurate and a pleasure to shoot. Only downside for me is it's a bit large. (I have small hands.) Great pistol to have as a 2nd, or plinker.
I've heard nothing on this thread about KelTec's and because of their initial cost they are disparaged quite a bit as "cheap". BUT - I purchased a new KelTec P11 last year and it has been a great little pistol. Accurate at self defense range, reliable, I'm very pleased with it. In fact I intend to purchase a P32 for concealed carry shortly. KelTec, made in America, by 'merican's, for 'mericans, and they stand by their products 100%. I kept wanting to send my P11 back to the factory for a "free" fluff n' buff but the dang thing just won't mess up to give me a reason. Lot's of pistol for little dinero.....
Last but not least, my little Sig P239 has always been extremely accurate, 100% reliable with any 9mm round I put thru it. It is the most accurate of all of my pistols (to be honest, the P1 is close), and a pleasure to shoot. Can't go wrong with a Sig.
Of course all of this is just my opinion, and there will certainly be no shortage of other folks with other opinions.. Anyway, opinions are like _ssholes.. (We all have one). Best Wishes