FTM - formula advice

FTM - formula feeding my 4 week old , & wondering what formula brand is the best to use? Similac , Enfamil , or other brands (suggestions)

I've tried Similac Pro-Advance ; seemed to make her fussy , gassy & constipated , now we are giving her Similac Pro-Sensitive to help with the fussiness & gas (she poops maybe every other day or every 2 days ....not sure if that's normal though)

....just wanting advice & suggestions....please no bashing or rude comments.