News flash!
Not all handguns are suitable for concealed carry. Even the ones that can be managed are usually best toted openly in a belt holster or under a heavy coat. Service revolvers generally fit into this category, though there are some very well-designed rigs that conceal them pretty well.
Others...like Redhawks and Super Blackhawks with 7.5 inch barrels aren't suited for any sort of concealed carry at all, and are best relegated to the hunting field....usually carried in a shoulder rig.
The revolvers that are easiest to carry are usually small, like the J-frame Smiths and the D-frame Colts. Because the cylinder usually presents the greatest challenge...the smaller the cylinder, the easier the gun carries. Barrel length is a second consideration.
Because autopistols are flat, they can be managed more easily in a larger caliber or capacity than the revolver...but that doesn't mean that a revolver is a bad choice for concealed carry or personal defense...even the 5-shot .38 Specials.