If you didn't say you were a reloader, I would have said get the .38 hands down.
I have both, and I have also heard that the .357 is less accurate with .38's than a .38. If there is, I can't shoot well enough to see it.
For me, I like the .357 better for practical reasons.
-I don't weigh every charge for .38s (maybe THAT's why I cant see the difference?). I do it by volume. In my experience, .38 likes being loaded on the top end of the powder charge. Lower charges for me lose accuracy. I worry much less about accidentally going .2grains over max shooting .38 from a .357.
-If you buy the .38, a shooting buddy will ask you if you want a big bag of .357 cases he is going to toss out otherwise. (this kind of stuff is a regular occurrence for me.)
-If you want to play with loads, pull out some .357 cases and make some +p, +p+, +p++ rounds. As long as the charge stays below .357 level for the same powder. (Don't play with low charges of 296, though.)
-Sometimes it's fun to shoot a low-recoiling magnum pistol (compared to your .44 Mag or a .454). Try some 125gr XTPs over w296 and you will be hooked.