Place the first 5 ingredients in the crockpot and whisk them together until the taco seasoning is dissolved in the liquid. Add the chicken breasts and coat with liquid. Cover and cook on low for 4-5 hours, until quinoa is cooked and chicken is tender. When both are done, shred the chicken breasts and stir. Top with cheeses and cover again for about 5 minutes to let it melt. Serve immediately with tortilla chips. Garnish with sour cream, if desired.