Daggers are just so much better then Twin fang in PvM since you can not only do more damage with them, you can attack monster with elements that makes them hard to hit, though you'd probably want a DDPP main guache + 10 in addition the the DDPT MG + 10 you use if you want to be able to really damage MVPs that have a super flee mode during their super flee mode. In PvP, Twin fang is like specialty tool to be used with daggers, not a stand alone weapon. You will still need daggers for the different swaps needed in PvP. In WoE, twin fang is just awesome since you can get an endow and don't have to worry about people trying to directly counter you and you alone. Get a DTT twin fang if you do decide to get one.
Another note, triple Abyss Knight is stronger on MVPs then double Abyss Knight and Turtle General since there the same modifier, however your do less damage to normal monsters or guardians.
edit: If you want a more versatile dagger, you can get a DDPS MG +10 or DDP gladius + 10 (depending on which one you prefer) since it will boost your soul destroyer damage.
A TTT suiken does 4.76% less damage then a TTH suiken on demi-humans so for versatility I would get a TTT suiken. If you make a second one, then i would get a TTH suiken.