In addition, the leaders of the First Crusade deserve credit for (mostly) putting their differences aside and trying to work as a unified army. Bohemond, due to having the most war experience, was voted as the overall commander, but he still had to consult the other leaders when a big decision had to be made.

By contrast, a lot of later Crusades included several Kings with large egos that made it very difficult to work with one another. Of course, that's only one factor in why later Crusades failed. The Fourth Crusade, for all its twists and turns, showed remarkable cohesion and that may well be because it was a "Princes" crusades made up of Counts, Dukes, and whatnot that were prepared to fight under a single elected leader.