Which mac foundation to buy?

i wanted to buy either mac studio fix or studio sculpt foundation dont know which one to buy wanted more of a dewy look and also what shade would you recomnd i tend to go for more tan and darker shades than my skin tone?also i have tried the tester for a few days i am beggining to break out in spots i dont know if that has got to do with the foundation has any one else experienced this wit mac makep???