Quoting:
Buy a revolver with a transfer bar.
I'm a Ruger fan and carry a transfer-bar-equipped wheelgun, but I fully respect the S&W post-WW2 hammer-block safeties, and the hammer-block safeties used in more or less all Colt DA wheelguns with a swing-out cylinder going back to at least the WW1 era. So no, transfer bars are not the only safe way of getting fully-loaded safe carry in a revolver...the best hammer blocks are 99.99% as good.
S&W pre-WW2 hammer blocks are...flawed. Not THAT bad but...I would not recommend them for street carry and if I had to anyways, it would be hammer-on-empty (reducing ammo capacity by one).
On semi-autos: there are some semi-autos of such low quality that I would be forced to carry one chamber-empty if that was (God forbid) all I had available. Examples include horrible pot-metal stuff like a Davis or Lorcin that I otherwise wouldn't be caught dead with unless I had no choice at all, some older model small autos, some others on a case by case basis.
On a Series 70 or prior 1911 I would carry chamber loaded, but the moment I could I'd score a titanium firing pin. Less mass for that extremely rare case where it drops nose-first and the un-blocked steel firing pin might have enough momentum on it's own to crank a round off. The TI firing pins reduce the available inertia on the firing pin. The hammer itself is well and truly locked back even when carried cocked'n'locked and the thumb safety slips off, so that's not the issue. (The "Series 80" action freezes the firing pin itself from forward motion; I consider the older action with a TI pin 99.98% as safe as a "Series 80".) Then again the 1911 doesn't really fit my hands for some reason, nothing to do with safety.
But anyways...this is what I mean: this question should not ever be asked as a "general rule of thumb" thing - it's on a case by case basis, according to the gun, in which case you have to know your gun inside and out.
The way the question was phrased, the person asking it didn't appear to want to learn the specifics of an individual gun type. That's the only reason you'd phrase the question (or...well, for that matter,
answer it!) that way. And I'm sorry, but I disagree with any such apparent desire not to know how your gun works. I'm sorry if I came across as too strong but...the idea that one can have a gun and rely on it without knowing how it works...well...yeah, sorry, I have to call that a Bad Idea[tm].
I can cite a lot of cases in support of knowing how your gun works.
We had a shooting what...a year or two ago, in Richmond Va, corner grocery store, lunatic with a modern DA wheelgun versus local "character" but good guy armed with an Italian replica 1875 Remington, 45LC, 7.5" barrel, open-carry classic western holster
. Goblin walks in, shoots the store clerk twice without warning (minor wounds thank God), points his gun next at a 10yr-old kid's head, guy open-carrying the Remmie gets it into action and hits with the first shot. "Cowboy" ammo, doesn't do enough damage. Guy with the Remmie dives for cover behind a large ice chest/bucket thing, on hitting the ground he screws up the Remmie's trigger. Ooops. Never did find out for sure what broke but I suspect a bent brass triggerguard as is common on that model. But he knew his gun, knew that it would still fire slip-hammering with the thumb, fired three more times hitting with two for three hits out of four shots (damned good for three out of four shots fired with a broken gun!), nobody else hurt, goblin died. Outcome was about as good as it could get - because the guy knew his gun's quirks. Weird carry choice, low-grade ammo, low rate of fire, didn't matter. (Oh yeah: no safety, so it was loaded five-up, and he finished the fight with one round held in reserve and unfired once the goblin ran his gun dry.)
Know. Your. Gun.
Seriously.
(Sidenote: this is even more important if the gun has been individually modified, such as the aforementioned TI firing pin in a classic 1911 pattern. If you bought it used, was it modded? If you don't know the answer to that question, ya oughta find out, right? Start by taking it totally apart, check everything, function-test it, test-fire it, etc.)