The level of performance is related to the task. For self defense, a two inch barrel .44 magnum may be adequate. With the right load, it could reach out much further. Ease of use and comfort will suffer. If 50 yards or so is all you intend to use it for, I think any of those lengths should work well enough. Just understand the shorter barrels, while as intrinsically accurate as the longer tubes, are much harder to shoot accurately. Elmer Keith seemed to love his 4" guns. Hard to argue with his results!