I test rode both CF and Ti frames pretty extensively before deciding what bike to get. I chose CF.

Both are expensive. Both are lightweight. Both are a tremendous pleasure to ride. You won't go seriously wrong either way.

For me, the difference was in how they felt when riding over rough roads, gravel, etc. The CF frames, especially the good ones, absorbed those nicely. The Ti frames, in my experience, generally transmitted more high-frequency road vibration to key contact points like saddle and handlebars. I like to do occasionaly long-ish (~100-mile) rides, and I think I'd feel a bit more beat up after one of those on Ti than I do after one of those on carbon. On my current CF frame (Trek Madone SL) I can do a century, and while the legs may be tired and sore, the rest of me feels great.

I have heard anecdotally that some Ti frames suffer from rather flexy bottom brackets. I never experienced this, but I weigh about 145 pounds, so my experiences may not be representative of what a heavier rider would feel.