Only boss weapons I'd say are particularly good are Sacred Chime Hammer (if you like big-ass 2H weapons, this is by FAR the best in the game once dark-infused and then buffed with resonant weapon), Moonlight Greatsword (only for pure-int builds after the nerf), and the Dragonrider Bow/Bow of Want (the latter if you have 50ish faith). Defender's Shield is alright if you have spare bones to upgrade it and you didn't get lucky with an Old Knight Shield in the first hour of the game.
Most disappointing by far I'd say is the Defender's Greatsword. People talked that thing up like it was something really special for a 50 faith build, but it's not even as good as a fucking Lightning Claymore +10. Ruler's Sword too, since the thing is completely broken and doesn't actually scale off the souls you carry at all.
I just ate all the other souls, aside from the ones that gave useful spells like Toxic Mist, Flame Weapon, etc.