With regard to the mental health consequences of battling to breastfeed, this is such an individual thing; no one should generalise.
If someone traces their own mental ill-health to 'obsession with milk intake', as bobbyswish thinks happens with her, then of course considering infant feeding is going to be high on her agenda the next time round, added to concerns about exhaustion and isolation, which she says were part of the picture as well. I do agree that a mother's mental well-being is important not just for her but for her baby.
But 'obsession with milk intake' may be no better with formula milk. How do you know that the baby needed 4 oz or 6 oz at any particular time, and not 3 oz or 8 oz? Reading bottle feeding threads on mumsnet reveals that worries (if not actual obsessions) about intake with formula feeding are not uncommon.
Exhaustion and isolation are not restricted to breastfeeding, either - not by a mile. I think it is a real shame if breastfeeding is thought to lead to either or both of these - life as a new mother should be supported and eased, so breastfeeding barriers are lifted and so breastfeeding becomes enabled.
bobbyswish - in your case, I totally understand that you feel you have been there once and it was not a good choice for you and your baby and you want to do something else which you judge will be better for both of you...fair dos!
Try not to belittle the choice of others, though, won't you, by avoiding phrases such as 'current breast is best thinking' as if the choice to breastfeed is a whim based on fashion
Hope things work out for you.