(Photo: Flickr/Kenneth Lu)
Toothpastes are really a matter of personal preference.
Almost all of the toothpastes today contain fluoride for cavity prevention and many have some type of peroxide compound included for whitening. The important thing really is getting the toothbrush in your mouth and not so much the toothpaste that you use.
I personally like Aqua Fresh Extreme. It is really no better than any of the other toothpastes, but I like the taste.
There are toothpastes like Sensodyne and Pronamel that have some desensitizing agents in them. Crest and Colgate have toothpastes available like this, too, for people who have very sensitive teeth that get pain when hot and cold foods touch the teeth.
Some people prefer Natural toothpastes like Tom's of Maine that contain no fluoride. You can also make your own toothpaste by combing some peroxide with baking soda and making a slurry out of it. It is inexpensive and does well.
Another toothpaste that I would recommend is Peroxidase. This toothpaste has a good refreshing flavor and has a bubbling action that makes your gums feel clean.
Again, all of them work about the same. Find one that you like and use it.
Finally, remember to change your toothbrush once a month. The bristles get frayed after about that long and end up pushing the debris under your gum instead of away from it.