Brown
The vast majority of brown sugar is simply white sugar with molasses added back in. Interestingly, molasses occurs naturally in sugar - but manufacturers bleach out the molasses to produce white sugar. White sugar is transformed into brown sugar by the reintroduction of molasses in carefully measured amounts to control the color and consistency. As such, it’s accurate to say that most brown sugar is even more processed than white sugar.
Because of the molasses, brown sugar does have trace amounts of certain minerals - but not in any significant quantity. There’s really no nutritional advantage between the two sugars.
Instead of trying to figure out which sugars are healthier, it makes more sense to spend that time and energy developing strategies for reducing added sugar from your diet.