I have never handled a 557, but have two Win 70's, my first a pre 64 model, the other from the early 80's, both excellent rifles, but I prefer the pre 64 controlled feed vs the push feed on the newer model.
I have a CZ 527, and a 550 Safari Classic, one a micro, the other a big heavy rifle. The thing I like best is the set trigger on the CZ. For some reason CZ does not put the anti bind lug or guide on the bolt, so the bolt can be sticky in operation, especially when new, and in my opinion never as smooth as the Winchester, otherwise a fine rifle. I like them well enough that I have another 527 in 6.5 Grendel on order.