I would suggest that if you had to take out cows milk you be ready to have to switch to a lactos free or even a soy formula. If there's an intolerance to milk you'll need these.
We used Parents Choice and now Enfapro. The Parents Choice is the Walmart brand and our LO did very well on it, he doctor switched her to a 6 months + formula because she is very tall and he wants her to get extra calsium, and due to constipation, less iron.
When your LO starts the iron may cause some tummy upset for the first few days, thats normal because of what iron is.
I suggest a talk with your doctor about if you need to go with the soy, or lactos free, or if you need iron free. They'll be able to help you better deside.