Omega 3 being a polyunsaturated fat is good for heart health. A ratio of 3:1 EPA:DHA is preferred because while DHA increases LDL, EPA and DHA are co-dependent. Avoid Omega 3-6-9, as, while Omega 9 is great, Omega 6 is another source of inflammation and most of us get plenty of it from cooking oils and whatever processed foods we consume.
DHA is vital for brain health, especially for developing children and the elderly. The ratio of EPA:DHA would lean towards higher DHA when used for brain health, but since DHA increases LDL, it must be used with caution.