Beats me.

Go to a rental range, try both, & see what you like.

I’m just a dyed-in-the-wool revolver guy. I’ve been playing with a Glock 22 and 3913 lately. I sorta see the attraction of the latter. Also a CZ-75C I tried at a rental range. The Glock, not so much.

I carry a K-frame .38 everywhere I go. It’s just what I know best.

Here’s one tip:

Revolver or auto, with the right holster and clothing selection, there is no reason to settle for a small-frame gun. Your ability to hit goes up considerably with larger-frame guns & longer barrels. IDK much about M&Ps (I have shot one), but it doesn’t look as though a compact or even full size would be much harder to conceal than a Shield, or that much extra weight in the right holster. I absolutely prefer a K-frame to J, and can carry comfortably all day in 100-degree heat (I live in Texas.)

On second thought, that’s no discomfort from carrying my revolver, plenty from the heat.