JYB is right; too many variables. My bike choices are entirely driven by handlebars.

I like Cinelli 66 and 64. So I have to have a Cinelli stem.
I have to have a Cinelli stem, so I need a 1" threaded headset and fork.
I have to have a 1" threaded fork, and the ones I like are attached to steel bikes.
I have a carbon bike that looks like a steel bike, but it has Cinelli handlebars, so it's cool.
I have an aluminum bike that looks like a steel bike, but it has Cinelli handlebars, so it's cool.
I have a carbon bike that looks like a space ship, and I'll get Cinelli bars and stem on it sooner or later.
I have a carbon bike that looks like a Schwinn Continental, and the poor thing has to make do with carbon bars.

See, it's not about the bike, it's the bars.