Saddles can be categorized by these attributes, in roughly descending order of importance: butt width (width at the widest point), width between the thighs, length, profile contour (flat or scooped), contour under the butt (flat or rounded), side skirts (present or absent), and thickness and density of padding. For instance, my profile is medium width at the butt, kinda narrow between the legs, shallow scooped profile, long, flattish under the butt, side skirts, and firm dense padding. I can pretty much look at a saddle and tell if it will work for me. My favorites are Bontrager's Serano (medium width) and Selle Italia's 1990 Edition Flite.

Determine your saddle type and look for those with matching attributes.