If you're gong to shoot predominately .357 magnums, I'd go with a full-lug GP100; if you're going to be shooting predominately .38 Special/.38 Special +P or lighter .357 Magnums, the MC would be a good choice in my opinion. But hey, it'll be your gun, so choose whichever feels right and best for you. Frankly, probably the biggest decision criteria would be choosing the variant with the sights/sight picture that you prefer, at least for me.
Ruger CS will make things right as necessary, or most corrective/cleanup work can be provided by a good local gunsmith if needed or desired.
Best, Jon