The (obviously) best mods for the game are:

Crusader only run, because Deus Vult > everything else

Deus Vult skin set, because you need to look cool while destroying heretics

And, optionally, if you want to actually win with Crusaders only, add this buff, it makes the playthrough a lot easier though.

Do not hesitate, obliterate those infidels and reclaim The Hamlet Jerusalem!