Store Brand Formula

My 3wk old son is has been on Similac Pro Advanced since day 1. As most of you may all know Similac is quite pricey. I was considering switching him to the store brand equivalent of the Similac. I already spoke to his pediatrician and they told me as long as he has no problems with it the switch should be fine. Can any of you moms recommend a particular store brand that worked for you? Pros and cons? I’m trying to do all my research before making the switch. Thank you in advance for any and all feedback!