Monitors. Pros - Low input lag, fits on a desk, and uses less energy. Cons - Too small for some, less input options generally, and will cost more per inch compared to cheap tvs.
TVs. Pros - Comes in larger sizes, surplus of HDMI connections, and always come with speakers. Cons - Generally have noticeable input lag, not designed to go on desk due to large size, and colors can come really saturated out of the box and require much setup and color correction.