So currently the "may issue" rules stipulate that you can only have 3 guns on your permit that you can carry. You are also limited to 10 rounds, as that law is not changing anytime soon.
Which guns do you choose?
One of each of these sizes would cover all possibilities. There is no point in having a double stack 9mm if you're limited to ten rounds. It is best in that case to go with a gun built around an 8-10 round magazine in 40 S&W, 10mm, or 45 ACP.
1) Pocket size
Semi-Auto: Kahr PM9, Ruger LCP, SIG P938, Colt Mustang XSP, etc.
Revolver: S&W J-Frame, Ruger LCR, etc.
2) Small
Semi-Auto: Either a single stack 9mm such as a Kahr K9, Glock 26, Glock 42 etc.
Revolver: Ruger SP101 (2 1/4" barrel), S&W K-Frame with 3" barrel, S&W Model 640 in 357 Magnum, etc.
3) Mid-size
S&W M&P 45 Compact (Glock 19 sized), Glock 30
Revolver: S&W Model 686, Ruger GP100 with either 3" or 4" barrel, S&W N-Frame with shorter barrel
Alternatively, carry a larger gun and have a pocket gun available. I do prefer to have two of my primary EDC guns in case one has a problem. The small or pocket gun is the backup or the deep carry gun. I would probably go with:
Semi-Auto: 2 S&W M&P 45 Compacts and a Kahr PM9.
Revolver: 2 Ruger GP100s (one with 3" barrel and one with 4" barrel), S&W Model 640 in 357 Magnum.