What is the best contraception option for very fertile couples e.g high risk of pregnancy no issues getting pregnant from either partner?

Hard to say: This selection must be individualized. The medical history of the woman may rule out some forms. The degree of forgetfulness may eliminate a daily pill. Condoms are relatively cheep & effective if used properly but may not be desired. A copper IUD can give 5 yrs or more of constant protection but is uncomfortable to place. A discussion with your doc would be the best plan to start selection.