Each of your 3 methods of creating effects will produce a slightly different effect.
The Dry Ice would be the easiest to do and the mist will tend to hug lower to the subject matter and be the cleanest. The Fog Machine will go everywhere and you also want to be sure to protect your lense with a filter since "fog juice" is made from seaweed (the glycols found about this from a sound and light pro), and could leave a film on the lense if you shoot for a while and use a lot of juice. As to the mister thing I bet it wouldn't look as fogish as the other two methods and of course your product will get wet.
Here is a home made fog machine link using an old iron and your own fog juice which you can control the mix on (does not use the seaweedbased glycerin but whatever type of glycerin that you find-one thing with true fog juice the stuff is made with high grade products and you will be breathing the stuff) With Haloween right now you should be able to find a fog machine and supplies more redially than during other times of the year.
http://softlyspokenmagicspells.com/halloween/fog.html
May not be quite as healthy but what about just plain smoke? Won't be quite as bright but may be better in producing the effect that you want.