Since your desire is to feed the 38 for general purpose use, which I assume would include loads with velocities as low as 700 fps, the 160 gr FN would be best. It can be driven at full magnum velocities in the magnum, even in plain base, though a gas check design is best for full magnum loads, whiclh will be generating velocities upwards of 1600 fps.
Meplat of the FN is .215 smaller than body diameter, while meplat of the XS is .90 smaller than body, which makes it a mean defense bullet, but it must be driven at full 38 +P power to get good stability.
The OWC has a meplat .030 smaller than body, but I don't recommend using it where serious deep penetration is needed. It's best use on live targets is when it is restrictied to body weights probably under 125 pounds or so. It is the quickest killer with 38 velocities though.
For larger game up to considerable larger than Carabou, I would recommend the 180 gr FN, gas checked, so it delivers the maximum velocity potential, and driven at magnum power levels.