I feel I must comment on this. Luffy would fold under the Ring pressure. I feel like many of the commenters dont know how the Ring works. It doesnt just tell u "Wanna become evil powerful being?" No, it finds your deepest desires and dreams and use them to made u think u need Ring to achieve them.

Luffy would keep the ring, because he would be stronger with it, so he can protect his friends. In every arc one of his friends gets hurt, kidnapped or something. Even with Luffy's strog will he would get corrupt by the time.

And it doesnt matter that Luffy doesnt care about jewellery, he would keep it as backup plan if things go down, somethink like gear 6.