HEX Performance Free + Clear Advanced Laundry Detergent
Because I don't have the luxury of having laundry at my house, I am big fan of HEX Performance Free + Clear Advanced Laundry Detergent ($9). While it's also available in large bottles ($9), the single pods make it easier to deal with when I am lugging all of my gear to the neighborhood laundromat.
Beyond convenience, Hex really works to get foul odors out of stinky workout clothing. The biodegradable, eco-friendly formula is made to work on synthetic material (like workout gear) and it leaves behind a nice, light scent that never overpowers clothing.