1, 2, and 4 are under exposed.
In #3 the dog is under exposed.
IMO the best of the group, by a large margin, is the last one..
It will help you if you were to learn more about how your camera meters light, and what metering modes your cameras have available for you to use.
There usually 3 light metering modes available Spot, Center-weighted, and Matrix (Nikon)/Multi-Segment (Sony)/ Evaluative (Canon). Understanding Camera Metering and Exposure Camera Exposure: Aperture, ISO & Shutter Speed
The camera B&W (monotone) setting generally produces a photo that has poor contrast values.
Using an image editing application to manipulate the colors in a color photo to make a B&W final image usually produces a better B&W image.