The parameters, as stated in the opening post, indeed seem strange. Why not just ask which revolver one would own in addition to an LCR, assuming these were one's only two revolvers?
Ruger GP100, 4" barrel, adjustable sights. Period. I would give the same answer if asked what my one and only revolver would be. Amazingly concealable, yet very shootable. The pre-Hogue factory grip is perfect for my hands, and I retain skill with a GP100 for a quite long time, a characteristic only shared with K/L-framed S&W revolvers. Ruger has the edge due to its perfect-for-me grip, easier disassembly for detailed cleaning, and a tougher coil mainspring. I've experienced an S&W mainspring failure, and no, the spring had not been modified.
I would much rather have a GP100 and an SP101, than a GP100 and an LCR.