Dual rank or single rank?

I’ve seen multiple sources online stating that single or dual rank are faster than the other. I’m looking to upgrade my ram and due to 1x32GB stick and 2x16GB being virtually the same in price (~£3 difference), I’ve looked into performance to make my decision. I have a reasonable knowledge of computers and to me both sides seem to have valid points. One side say dual rank is fater as it has higher bandwidth, whereas the other says single rank has faster access due to only using 1 clock cycle as opposed to 2 for dual rank. Do both formats have individual merits and similar performance, or are half of these sources wrong and there is clear winner?