Breastfeeding VS Formula

First time mom and really need input. I orignially planned to formula feed, for personal reasons.. But after my OB Work-Up today, and talking with my Midwife, I am possibly considering breastfeeding. What I want is input from mothers who have done both! If you have done both formula feeding and breatfeeding, did you notice any differences in your baby? Or if you've had multiple children, and breastfed one and formula fed the other, did you notice any difference in each baby? I hope I'm wording this right.. I'm just so stressed about this, and I know what I want to say in my mind.. lol. Thanks so much!