Nan vs similac or other formula. What do you mummies look for in the formula?

I also searching for an answer too. I'm a first time mummy and had been trial and error, in fact I tired all brands before I decided to settle with friso. For my baby, he unable to tk s26 and similac as it was too heaty for him. Phlegm occurred. Constipation for dumex and nan he manage a 90% growth with friso intake :)