Technically, Ripple also has limited supply. The overall quantity of XRP does not increase; they are already pre-mined, remember? It's just that the Ripple company is holding rather big chunk of the supply, and they are planning to gradually release them into the circulating supply. The overall supply of xrp is actually decreasing, for some xrp is lost per transaction.

Supply would only matter for coins that does not have a limited supply, perhaps like Ether.