I've got several .357mags, and shoot .38spl almost exclusively. Why? My shooting consists mainly of match shooting & practice, and since there's no need for .357mag power, .38spl is the better tool for that.
Also, my main match (IDPA) gun, a 4" L-frame 686, has 70k+ rounds through it. Competition is tough enough on guns, so there's no need to accelerate wear and tear with 35 kPSI ammo when 17kPSI will do.
Yeah, then there's recoil and muzzle blast. I'll usually shoot 200-ish rounds per range session. A few .357s are fun, but beyond that, it gets old quickly.
I don't download .357mags because I'm still dealing with a relatively long case, making quick reloads trickier.
A .357mag revolver is more versatile than a dedicated .38spl, which is why the former are often more expensive (more demand). OTOH, I certainly wouldn't rule out a nice .38spl revolver if it's in good condition and priced fairly.