If you want moist, tender chicken tacos, you gotta go with the chicken thighs. I know that we've all been conditioned as Americans to go with white meat, but the fat inside chicken thighs makes the most juicy, drippy, amazing tacos of your dreams. You CAN use chicken breast, but your tacos will not be as moist and flavorful. (you will still have tacos at the end of the day, of course. Just add more sour cream )