I like both. Kaminsky is more of a true center, but I'm not sure he is going to bulk up the way Olynyk has. Kaminsky seems to be a better shot-blocker though. His back-to-the basket post game is better too.
Olynyk is a different player. He has the ability to play both forward spots also, which Kaminsky can't do. He is a better passer and play-maker than Kaminsky ever will be. Also, Olynyk can do a bit more with his jumpshot (fade-aways, step-backs, coming off down screens for jumpers, etc.) than Kaminsky.
They have their similarities, but they bring different strengths to their team. I like our guy a bit better, especially because of his dedication to improve his athleticism and game. Not that Kaminsky won't dedicate himself too, but I like that Olynyk has a track record of hard work and improvement at the NBA level.