If you want to get 1 offensive item on Leona in ascension, what's the best one?

If you want to go: Boots 4 Defensive Item 1 Offensive Item

What would be the best one for her? Ever, since Riot reduced her damaged on her abilities but reduced the cooldown on all her skills, I did notice that she can use her auto -> Q -> Auto(3 auto attacks) a lot more often than before. With max cdr, your Q cooldown used to be 4.2 seconds, now it's 3 seconds, meaning you can do 2 extra auto attacks every 3 seconds. Does this mean AD item is better? If so or not, what's the 1 item that is the best for her?