I like the first cover better. It's nicely evocative of vintage paperback SF novel covers. This, while well-rendered, is more of a generic floating-heads-in-space cover, aside from that buttressed palace or whatever in the background (perhaps a rendering of how Ellison originally described the Guardian or its environs?).
I miss those old vintage paperback SF covers myself. I think they're far more interesting then photoshopping the characters onto a cover. The photoshops almost always look awful and unimaginative.