Like everything, your preferences matter and we can't answer that for you. But since you asked, you obviously want to know what our preferences are.
I bought a 640-1 which is an older model .357 magnum shrouded hammer J-frame. The shrouded hammer is definitely better for concealment, especially in an ankle holster where a hammer spur can catch on clothing. But you lose the single action pull. This can be mitigated by replacing the rebound spring and smoothing the surfaces around the rebound slide and hammer. This is not hard to do yourself, but if you mess it up, you can easily destroy the pistol. I would never recommend using a lighter mainspring because this will increase the chances of a light primer strike. An extended firing pin doesn't always solve this problem.
I have carried it in an ankle holster, and it is heavy enough to change the way you walk. It will also noticeably distort the shape of a jacket pocket. It is fairly comfortable in an IWB holster, but with the large cylinder it will never be as comfortable as a semi-auto.
As with any J-frame, your accuracy is limited by the short sight axis and poor sights. But with practice you will easily be able to hit a man in the chest at 7-10 yards. I have Crimson Trace grips on mine, but I never recommend relying on a laser for a handgun. It is there for times when my ability to aim through the sights is compromised.
I bought the .357 magnum precisely because it can fire .357 magnum, .38 special, and .38 special +P. The extra weight and strength of the gun is desirable for durability. Frankly, firing .357 magnum rounds out of this pistol is awful. The first round stings, the second round hurts, and the third round really hurts. If you use it at night against an attacker, you will be deaf and blind after the first shot although not as bad off as the poor sucker on the other end of this thing.
But I have the choice to load it with three different types of rounds. Right now it is loaded with .38 special +P. If I found myself out of ammo and the first box I found was .357, I won't be out of luck. For me, versatility in ammo is a HIGH priority. For example, I have a conversion barrel for my .40 cal to 9mm so I can use either ammo type. Similary, .357 gives me options while a .38 special does not.
In my view, the ONLY reason to buy an airweight is if you absolutely cannot stand to carry a heavier piece. After all, a handgun is of no use to you if you are not carrying it. And a .38 special was used as a self-defense round for decades. If a few shots is all you need and you rarely need them, then why not go for the lightweight pea shooter. As pea shooters go, .38 special is the Queen and 9mm is the King.
Just don't expect spectacular results from this under-powered cartridge. A .357 magnum is near the top of the man-killing effects range while .38 special is near the bottom along with 9mm. Handguns kill by damaging major organs and opening up blood vessels. A larger round gives you a greater chance of doing this. ALL handguns are under-powered compared to the devastating effects of rifles and shotguns.
While I value my .357 snubbie and wouldn't part with it, my go-to gun for concealed carry would likely be my Kahr K-40. The 40 cal is near the top of man-killing capability, and the Kahr is a flat, lightweight weapon. My Glock 23, also in .40 cal, would be next. I have no worries about their reliability.
Revolvers have an exaggerated reputation for reliability. I assure you that my many revolvers have and will fail from time to time. In most cases, you just have to pull the trigger again, but if a revolver does jam, you might as well use it like a rock.
The best reason for using a revolver is to leave no shell casings behind. I'll leave it up to you to decide whether that is important to you.