Baby formula

Any good baby formula brand for 5m+ baby. Tried Nan Optipro when she’s new born, she hates it then change to Bellamys Organic she accept the taste but her tongue have black stain after consuming it so then changed to Enfamil Gentlease she can accept it also and have drink quite a few tins already, but recently she’s rejecting it not sure if she’s bored of the formula taste or other reason, so I’m thinking to try other brand since she’s turning 6month soon. Any recommendations?