I used navel oranges (which are seedless, wonderfully sweet, and juicy) in this immune juice, as it's what I had on hand. However, it's important to note that navel oranges contain a compound that becomes more bitter over time and is best consumed within 24 hours. You can experiment with any type of orange for this juice, though. My other favorites include: Valencia oranges: These are naturally sweet, contain few seeds, are available most of the year, and won't become bitter. Blood oranges: While in season, blood oranges are a great option as they're packed with antioxidants and have a sweet-tart flavor and beautiful pink-red color. Tangerines OR Clementines: Available almost year-round, small, sweet, and juicy.