In terms of both ~ and ~; in terms of ~ as well as ~; from the perspective of both ~ and ~ From the perspective of the colour as well as the design, this suit is a good match for you
Ref # A Dictionary of Advanced Japanese Grammar p628
LR
{NOUN1 + といい} + {NOUN2 + といい}
LR
This grammatical structure is used to present multiple perspectives when describing a person or a thing. It is often used to provide the speaker's / writer's judgment of the person or thing.
LR
Could it be that いい is the stem of the verb 言う? Or perhaps the expression originated from that?