What's the intended purpose of this gun? SD, hunting, or...? What calibers are you considering?
THAT SAID... here are some general rules.
IMHO there are only a handful of S&W models that should categorically be avoided if you want a "shooter": the .32 Hand Ejector Model of 1896, very early Airweight models with aluminum alloy cylinders, and the .22 Hand Ejector aka "Ladysmith". The .32HE Model of 1896 should be avoided because its lockwork mechanism is substantially different from any other S&W revolver ever made, and production was relatively low (and ended 110 years ago!), so if you break something, you're most likely SOL. The early Airweight cylinders are UNSAFE TO FIRE with full-power .38Spl ammo, or even low-velocity target loads in some cases, but these guns are rare. The .22HE is too delicate overall to withstand repeated firing, particularly double-action.
S&W revolvers made prior to 1914-1919- the exact year depends on the frame size and model- do not have any type of hammer blocking mechanism. They are NOT safe to carry with a live round under the hammer. The early models also have different internal lockwork than later models, making parts harder to find.
The initial "wing" or "pivoting" hammer block used prior to 1944- while better than nothing- has a tendency to break off or jam in the disengaged position with no indication to the shooter. Opinions vary on the wisdom of carrying a S&W with this hammer block and a live round under the hammer. The post-1944 sliding design is far superior and is used to this day; early postwar S&Ws with the new hammer block can be identified by an "S" prefix that was used across the product line, although it was rapidly superseded by the "C" prefix on fixed-sight K frames as production exceeded 2 million(!).
S&W revolvers made prior to 1920-1925- the exact year depends on the frame size and model- do not have heat treated cylinders, making extended use with "hot" ammo an iffy proposition.
S&W officially recommends not firing .38Spl+P ammo in pre-1957 revolvers without model numbers.
Pre-1987 .44Mag Smiths had some problems with lockwork "shooting loose" from recoil when subjected to heavy use with full-power Magnum loads using heavy bullets. S&W cooked up improved lockwork, titled it the "Endurance Package", and installed it in all Model 29s and 629s starting with the 29-3E ("E" for Endurance") and 629-1E. These revolvers have gone through several engineering revisions and successive decades of production since then, all of which have the improved mechanism. However, the early guns usually stand up fine to typical use by most shooters- i.e. a diet of mostly .44Spl with a few Magnum loads now and then. This is good, because there are a LOT of M29-2's and M29-3's out there; most of the "shooter grade" M29's I've seen are these versions.
"Smokey, this is not 'Nam. This is bowling. There are rules... MARK IT ZERO!!" - Walter Sobchak