So lost on formula

Esther • I’m better than horrible. EMT and Respiratory Therapist

So I’m due in 5 weeks and plan on combination feeding assuming I don’t have issues breast feeding. I stated to research formulas as I should have some before the baby comes and I’m so lost. I think I want to try the Gerber brand first, but I’ve also signed up for Enfomil. I know every baby is different but what’s your preference and why? Also, how much should I get? I don’t want to stock up too heavy on one brand and have it not work for my baby