Basically, due to photosynthesis, all plants release oxygen into the environment. However, during respiration, they will also use oxygen as plants are aerobic. That said, while I was unable to locate the best oxygen producers, I will give a list of hardy plants that are excellent to grow in the home. Begonia, zebra plant, spider plant, ficus, philodendron, orchids are all excellent plants to grow in the home. Any succulents that you find in your local gardening store are also quite easy to propagate. Remember, pot size is a factor as you don't want your plants pot-bound, adequate light, temperatures between 60-80 degrees Fahrenheit and specialized houseplant soil which contains the proper nutrients.