The best toothbrush is soft with rounded bristles, which can be either a manual or a power brush. Hard tooth bristles aren't recommended because they can scrape your teeth and cause gum recession. You don't need to scrub your teeth to clean them -- gently brush the plaque and food debris off them.
Remember to replace your toothbrush at least every three months. Oral bacteria, as well as other environmental effects from your bathroom, can build up on your toothbrush. A fresh toothbrush ensures you're keeping your teeth healthy.