Carbon. Outside the luddite world, Ti as a road frame material is being called into question, even in the Mtb world too, too much of a premium for what you can pretty much get from a steel set up these days, your lucky if there is half a pound in it. Also I'm guessing your riding isn't big day out epics and more but a hoon about in the evenings, now not having ridden either obviously I'd say the carbon frame should be more fun and racey. Carbon when done right should be stiff in the right places and comfy in others, harder to do with Ti. I still fancy ti of course there is that je ne se ti about it, I've been eyeing a Kinesis frame as a crosser/tourer/epicy thing, but the truth is I don't have the time for the tour/epic so its a pipedream to the mo.
Edit: Forgot to add, my carbon road bike is brilliant!
Edit: Forgot to add, my carbon road bike is brilliant!