Hi mama! Based sa prices mo, Similac 3 is mas affordable both sa regular store at Mercury, so kung budget-conscious ka, that's the better option, but honestly, ang mas importante is kung ano ang tummy ng baby mo ang comfortable with kasi puwede magka-upset stomach if bigla ang switch. A few of us tried changing formulas, and one of my friends' baby had a hard time, so siguro gradual ang transition if possible, or check din with your baby's doctor kung ano ang best brand para sa kanya, especially if may sensitive stomach siya!