B&W conversions, how do you decide

Thank you everyone for your thoughts and feedback.

I prefer the colored version ... perhaps to have the color slightly warmer ...

Normally, monochrome works well for portraits, but in this case, I personally prefer the colour image. The warm and smooth complexion of the innocent child's face needs colour to be brought out, and with such an adorable child and his expression, it would be a waste to throw that warmth away. I don't think the monochrome can convey the same feeling. The other colours in the photo work well together too and don't distract from the subject. Try bouncing your eyes between the two images. I think eventually, your eyes would prefer the colour one. 🙂

IMO; 
One set of images that lend themselves to B&W are the ones with strong graphic or geometric elements. If the “Point” of the image is what I call light-and-shadow/line-and-shape, then B&W may be the best bet because monochrome emphasizes those abstracts, versus the real-life, in-person object. 

In a backhanded way, B&W is also good when there may be flaws in the original that need to be hidden. There is no color-noise in B&W, for example, and because we are used to the concept of “grain” in film photography, luminance-noise tends to be more acceptable too, as well as soft-focus. 

In this case, I personally prefer the B&W because the original is a little soft, and the monochrome hides the dirty face, which some may find endearing, but I don’t. 

If you do your B&W developing outside the camera, there are many options to play with, including dynamic range adjustments (I use “curves” in Photoshop) and color filter effects (not tints, just simulating what B&W film would see when using different color filters).

In this fase the color version is better. Most of the time I know in front if it is for conversion or not.