Buy a saddle from a shop or company that allows returns or exchanges. The only way you can tell if a saddle fits you is to ride it, and everyone's different. A saddle that is comfortable for one person could be torture for someone else. If you find a saddle that fits, buy an extra one.

That said, lots of cyclists who have had trouble fining a comfortable saddle end up settling on Brooks, and the B17 model is often cited as their most comfortable. I rode B17s for several years until I tried a Fizik Vitesse. The Vitesse was just as comfortable as the B17 but weighed half a much, so I have put them on nearly all of my bikes now. I still have a B17 on my touring bike, however, because it looks so nice and I am less concerned about weight on that bike.