Both fine weapons, and I've carried 'em both.
Through the years of carrying legally concealed my tastes have evolved and I'll bet yours will too over time.
The 3" Model 65 S&W revolver (which I still have) gave way to a custom, 1990s era Colt Combat Elite, a full size 1911 auto.
Both gave way to this pair of LIGHTER handguns a few years ago . . . a then-new Kimber Ultra CDP (aluminum-framed, officer's sized 1911 w/nightsights, etc) AND my first S&W J-frame, a Model 36. Both weigh about 25 oz empty. And, although both these handguns are about the same "size," the J-frame was easier to pocket carry. That's when the Kimber started "hangin' around in the safe a lot. Both are still in my safe tonight, but they've given way yet again to a lighter-weight J-frame, the Model 37 Airweight.
Today, my "always" CCW firearm is the humble little S&W Model 37 Airweight (the aluminum framed version of the Model 36, for I've discovered that the only serious handguns that are light enough and small enough to carry concealed ALL the time are the Airweight J-frames!
Yeah, you can get a 637, or similar Airweight in .357 and, if that's what you want, go for it. You can get it in a 3" barrel version too. Concealable AND easy to shoot. Still . . . .357 ammo is very stout to shoot.
Frankly, I've competed in so many handgun matches through the years that I learned if one wants to win . . . they use equipment that is fast to draw, points quickly and recovers under recoil quickly as one swings to the next sight picture with maximum speed and efficiency. That rules out .357 ammo in a small handgun . . . but stoke .38 Special ammo in the same gun and you can shoot faster with utmost accuracy too!
You may have to go through this learning curve too before getting a CCW handgun that is eminently concealable and that also allows fully controllable follow-up shots with ultimate speed and consistency.
Eventually, if you are a competent handgunner, I suspect that one day you'll own a S&W Airweight revolver as your "always" (always on you) CCW handgun . . . stoked with .38 Special for all the right reasons!
Heck, I can even carry my little J frame + pocket holster in the front pockets of my gym shorts while mowing the lawn!!! Trouble comes when you aren't expecting it . . . but I'm "always" ready because I have a handgun that I can "always" conceal.
IMHO, having a .357 or .45ACP handgun SOMEWHERE ELSE ain't gonna help you when trouble comes like a lightning bolt piercing the night air!
Food for thought!
PS: When weather and wardrobe allow I STILL carry that Model 37 in the front pants pocket BUT . . . I'll also strap on either a .45 Auto (high cap, full-size 1911 or the Kimber . . . or the 3" Model 65. In colder weather, I'll strap on my custom, chopped barrel (to 3 1/4") big ol' S&W Model 25-2 . . . an N frame revolver in .45ACP! BUT . . . FOR CONCEALED ALWAYS . . . you can't beat a little J-frame! At least rent a J frame at a range somewhere and see what you think for "always" carry!