Both BK weapons are really good when you first get them, particularly the halberd on any sort of caster build. Heide and Fire are decent for a caster up until those become available. Really, though, any weapon with movesets you are comfortable is workable for at least the first half of the game on the initial playthrough. Once you get to the Sinner and beyond the door, its time to get a real weapon. Really, the only weapon I am disappointed with are the spears, but that's probably lingering overnerf from how uber they were in Demons Souls.