So what N frame is best for concealed carry?
The traditional carry gun would have been a 3 1/2" Model 27 (or pre-27, magnum or registered magnum or whatever). That's still a good one. S&W doesn't make it anymore, but there are older ones in abundance. The cylinder is pretty heavy with only 6 chambers of 357. I don't mind the overall weight, but the rotational inertia is hard on the gun. Those old revolvers weren't designed for the present age of 5x5 classifiers, bill drills, and the gun racing that pervades even "defensive" oriented training.
S&W does make the 4-inch 27 "Classic." It's similar to the traditional 3 1/2" guns. In a 4" N frame, there are also Models 29 and 629. The 629 comes in the half-lug and the full underlug. The new ones all lack the pinned barrel and recessed chambers. The MIM parts will probably hold up better than the older stamped and case(surface)-hardened parts of old, but are still best-suited to slow fire. They would at least be less costly and easier to fix or replace than an old 5-screw.
The modern carry gun might be the 2" or 2.6" guns. They feature 8-chambers for 357 but the 2.6" can also be had in 44. I find barrels this short to be annoying. They demand slow powders to develop the needed velocity and that results in high muzzle pressure and the worst blast and flash. They also have poor sights where the short sight radius becomes demanding. If large enough grips for good control are installed, they become imbalanced.
There's also the aluminum 329PD. I've talked to a couple of owners that like theirs, but personally I've had the worst result with scandium/aluminum framed revolvers. In my experience, they don't hold up. I'd rather carry the weight to have a durable gun for much practice and better control.
The last one I'll mention is the 4" 627 Pro Series with the slab-side barrel and 8 chambers.
Besides that, I know there are 5", 6", 6 1/2" and over 8" models, and there are a few other chamberings like 10mm, 41, 45 etc. Those chamberings come in fewer form-factors and none that are unique to them.
So what is the best N frame for carry?