Saddles are a very personal item. That said, perhaps the most important variation which is also not considered often by customers is the front-back profile of the saddle. Many people find a saddle with a pronounced dip allows greater stability for pedalling. Others like a flat profile as the raised frontal area can increase friction in that vital area. If you get a chance to try other peoples saddles follow your immediate impression and you will often be right. Bear in mind saddle angle is critical and anything other than horizontal is likely to cause problems if not down below then in your arms.