Ebonite Jaguar
Imperial Quantum (I think this was late 90's).
It seems to me that there have been only 4 major advances in ball technology during my bowling career. First came Urethane, then Urethane with two-piece core, then Reactive Resin, then Particle Technology. One might conclude that today's reactives are somewhat better than they were 10 years ago, but they certainly aren't as vastly different in reaction from each other as they are from the Urethane they replaced.