Since all the shapes are classic, I think it's a question of how much visual interest you want in a boot. The croco has the most; the plain black leather, the least; the patent, in between. How well will the different textures complement your skirts and dresses? If you're not sure, you could order more than one and experiment with the looks.
I fell for a pair of boots last year with bright color and visual interest (red patent) and as much fun as they are to wear, they require careful coordination with outfit and coat, and they are not for a day when I'm feeling faint of heart. So a bit of it is how much you want to be "out there" every day with your boots, as well as the way they work in your wardrobe.
I have a long slender calf as well and a 13-14' shaft is a little higher than a mid-calf boot. It's not a bad length for skirts, especially if it fits the calf really well, but if warmth is an issue, you may want something in the 15" range!