Both have their uses, but which might be better for you depends a lot on your local climate and how often you are around to hand spray. If you just need to provide drinking water and some humidity during the day when you aren't home, a mister would do that. If you live in an area where your home's humidity level is very low, using a mister alone may require that it run so often that it soaks everything too much. A fogger can "fill in the gaps" between misting cycles by raising the cage air humidity. You could also use a combination of hand spraying in morning and evening (for drinking) and a fogger cycling on and off with a timer during the rest of the day.
The little terrarium foggers can be fussy, hard to keep clean, and as they are usually put inside the cage, can be a hazard if your cham touches the reservoir while it is running. The unit creates fog by nebulizing water (very high frequency vibration). It produces some heat and electric current. It is much safer and more efficient to use a room humidifier set outside the cage and aim the fog with pvc or flexible pool tubing.
A mister will create larger water droplets and actually rain on the foliage. You'll have to work out some sort of drainage for the cage if you use it.