I don't think it matters what formula you use for acid reflex. My son is on Alimentum b/c he has milk soy protein intolerance and he is on Zantac for his acid reflex. Is your baby on med. for acid reflex?
Enfamil A.R. is made specifically for babies with reflux. My son has reflux and the only reason we didn't put him on is because he was already constipated, and the A.R. formula is thickened so we figured it would make him worse. He's on Enfamil Gentlease and does great. He still spits up here and there but nothing like what it was, and we haven't had to use his medication since he's been on it.
Truly, which ever one works best for you.
Good Start really helped my little one. We tried soy, we tried nutramagen (which she refused to eat a second time), but the Good Start helped her crying and pain the most.