I like 'em both, looks-wise. That's good 'cause I haven't AT ALL liked any of the other new-wave muscle-cars in that department, except maybe the Mustang, which is okay IMO. I love the Challenger shape. Why mess it up? And the Camaro is one of the freshest looks I've seen in a while.
I do, however, have a growing pet peeve with these narrow, slit-like windows that are getting popular. The Magnum has 'em, the HHR, some others, and now the new Camaro looks that way too. I haven't driven/ridden in any of them yet, but my wife had a rental Magnum recently and said it was a pain because you couldn't see anything. To actually enjoy DRIVING a car you need a good view out.