I love shell cordovan shoes and own two pairs of Alden leisure handsewns, one in color 8 (burgundy) and one in black (which I'm wearing today), as well as a pair of brown polo Darlton wingtips made by C&J. They have developed very broad creases and the creases are lighter than the surrounding leather, both features distinctive of shell cordovan. The coloration of all three shoes is subtly different than that of calfskin shoes. It's hard to describe, but the shine just has more depth to it.
Shell cordovan shoes take minimal care (I wipe them down and polish only the scuffs) and the material is *very* tough. Not long after buying my color 8 loafers, I ran over my foot with my desk chair while sitting in the chair (ouch!). I was more concerned with the possible damage to the shoes than the pain in my foot, but I had only an indentation across the vamp, which has actually disappeared over time.
I wear my shell cordovan shoes at every opportunity, so I found myself wearing the wingtips every other day last winter and I wear each pair of loafers at least once a week, and usually much more often, in the summer. The cordovan color is more versatile than either black or brown and might clue some people that your shoes are actually shell cordovan, if you care about such things. I actually like my brown shell cordovan shoes best because brown shell cordovan is harder to find than either black or cordovan colors and I *really* like the variation of brown shades across the shoes.
As to your question whether I prefer calfskin or shell cordovan shoes, my answer is "yes". I prefer calfskin or shell cordovan shoes on different days, depending on my mood. I love shell cordovan, but don't ask me to give up my calfskin shoes, either!