If you want 5 shots (whether .38 Spl or .357 Magnum), then maybe a M60 or Ruger SP101 3" would satisfy you. I have an older M36 .38 Spl 3" RB HB that is a dandy little 3" snub.
If you want 6 shots, then a K/L frame 3" would probably meet your needs.
While the type of holster and the cylinder thickness are more noticeable to some folks than to other folks, it's often the size/shape of the grip (and any added grip stocks) that usually create concealment considerations.
The barrel length difference between 3" & 4" isn't so much of a concealment issue, aside from considerations of the holster's design and position (high/low on the belt line), and whether you're going to be seated a lot.
It really comes down to how you perceive the "shoot-ability" of any particular make/model, once you narrow down the capacity to 5 or 6 rounds (or maybe 7 rounds, if you come across a 686-Plus in a 3" length).
Some folks might find they prefer to compromise in the size/weight to offset felt recoil concerns, and others might not mind the felt recoil and might prefer to look for the smallest overall size. Even overall weight is a subjective issue, as it may affect both felt recoil and daily carry considerations.
Figure out the directions in which you wish, or would just be willing, to accept, and see what guns fit for the intended role.
Ret LE Firearms inst & armorer