What prejudices, habits, and desires might prevent you from finding truth?
Any and all of our prejudices, habits and desires might stand in our way in the search for truth. Thomas Kuhn famously argues that to some extent physics can only progress because physicists eventually die, taking with them to the grave all their prejudices, habits and desires. If the search for truth is conducted by the more personal method of Socrates, the Buddha, the Oracle at Delphi, and perhaps this is more what you had in mind, then the problem becomes even more immediate, for we would stop making progress entirely when we die, and nobody else can pick up the baton.
As to which of them might be most likely to prevent us finding truth, I doubt there can be a definite answer. It would depend on what sort of truth we are looking for and where we are looking for it. The general solution for prejudices would be to adopt what meditators call ‘beginner’s mind’. For habits the solution is unfortunately a lot less obvious.
It may be that desire is the real issue, for at the very root of things it seems to be desire that sustains our prejudices and habits. Unyielding prejudices and habits may no longer be possible once desire is conquered. At any rate, for Buddhist practitioners the overcoming or transcendence of desire is a central goal. Not this or that desire, but all desires that are not useful and that might create prejudices and habits that cloud our view of truth. Prejudices and habits will wither away without the support of desire, so they say, allowing to see the world as it really is. So the question of which particular prejudices, habits and desires might prevent us finding truth would not really arise. It would be desire itself that is the problem, or our lack of control of it.
Of course, all this is theoretical. It would be wonderful if the problem of prejudices, habits and desires could be solved theoretically.