Formula

I was wondering is there a better formula that worked for your babies . My baby is almost 5 months old and the paediatrician said I can soon start giving him the starters gerber baby oatmeal mix . The only thing is that it asks for 160 ml of breastmilk or formula . I had frozen a lot of bags of milk when I was pumping but they seem to all have gone bad which sucks cuz they only a few months old the oldest is from May . Anyway my baby is eating every 2 hours so I don’t have time in between to pump 160 ml of milk and mix it in . So I was wondering what brand is best? I’ve heard lots of good things about similac.