That depends, under the crit cap without trinkets = B/C
B/D is better but ONLY once your gear gets you over the crit cap without a crit trinket.
Because crit loses so much value (in theory) after we reach the crit cap, that makes the crit bonus on the Phylactery useless after reaching it. So the haste on the Charred/Dislodged gives a bigger DPS gain. You won't expect to be using B/D until you have just about full 277 and/or the 277 Bonespike+Spindle.
I use Nibelung a lot too for RNG fun - when I use that I need the Phylactery for the crit cap, when I use the Bonespine+Spindle I can use two haste trinkets.
Now hold on, hold on. Crit doesn't lose "so much value". As it turns out, after the soft caps, haste is worth around 1,3 DPS per point, and crit around 1,1 DPS per point - thats how it is with my stats anyways. This is not a *huge* difference. Its a difference, granted, but not a huge one.
Of those the OP mentioned above, C and D are the better choices, simply because of the stats they provide *if* he is staying above the soft caps. If he falls below his soft crit cap, the Phyl and the Spyglass are more or less equal, and its a pure toss up between the two. Phyl has more potential for being devistating, cause popping starfall when the buff is up is a huge damage increase, whereas the Spyglass gives more of a steady bonus that is easier to count on.