Go by what fits you and your horse best. (I know that can be really hard to know if you are buying over the internet). Picking a saddle by what looks best is like buying a horse based only on it's color!
Also, consider what features you might like best. For instance, round skirts vs. square. Regular swells vs. the swept back bear-trap swells on the second one. The first saddle might have more of a rise to the seat, the 2nd one looks fairly flat, etc.
Are there any indications on which tree might fit your horse better?