Until now no one has been able to beat the speed of Stellar (maybe this is my experience in terms of transactions from Stellar).
Somehow Stellar is the fastest but maybe this is the development of Ripple too because these two coins are not much different for its CEO, Jed McCaleb.
Hopefully my guess is not wrong because this is my experience of Stellar and if there are other members who understand the fastest coin transaction speed, please reply to my thread!