Titanium.
I just love the material, the look, the feel, I have a small piece of a Suzuki GSX-R750 engine which is made from titanium, not because I'll ever use it, not because I have any affinity to Suzuki bikes, I just love having this small piece of titanium.
For me, carbon fibre (in all its guises) feels a man-made product, whereas titanium is natural. The difference is like the difference between nylon and cotton or between plastic and wood. Carbon (and nylon and plastic) all have their uses but (with reference to the generalisation requested in the OP) I inherently prefer titanium, cotton and wood.