Here they are pretty rare, the regular cragar ss's are about a dime a dozen here then next to them are torque thrust, but I've maybe seen one or two sets of keystones. I think it requires a certain style of car to make them look right.
There are several aftermarket wheel styles that I've always likes. The torque thrust/ Cragar SS's are really nice wheels, but they're probably also the most common. I like to see more of a variety. There's something to be said for being different than the rest of the crowd. - But as you've stated, some wheels look better on certain cars than others. The Cragar SS probably looks good on every car it goes on. We've probably become conditioned to like them from having seen them on so many nice cars over the years.
I think the additional black in the wheel centers of the Keystones makes them really stand out on a black car. - The deeper the dish, the more 3-dimensional they seem to be when the rim reflects the chrome/black centers.
I was discussing wheel choices earlier today with another guy. He had me come over to help him install a new wiring harness in an Olds 4 4 2. It had a set of the Cutlass color matched rally wheels on it and I told him I thought it looked 'girly'. He agreed. The car belonged to a friend of his and they were going to have to buy a different set of wheels for it because they didn't have disc brake clearance. I'm not sure what they'll end up with. Now I don't mean to imply that either of us hated those factory wheels and I'd probably have kept them if it was my car (and there was no clearance problems). But they're far from being one of my favorite wheel styles.