KFMs need to Counter/Dash Resist in order to maintain Focus levels and proc skills. They do poor DPS if nothing is attacking them.
Both BM and KFM are reliant on being attacked. BM can reg chi after a block, thus he, too, would lose a lot of DPS if not tanking. The reason KFM is preferred if both are in the group is due to BM still having a good Chi regen if he’s not tanking. BM will lose damage, but not as much as KFM if not tanking.
KFMs actually have some +Threat talents to make them clearly able to hold aggro over anything
BM has actually more threat than KFM. Their DPS is the same, however the +300% threat attack of BM does more Blade & Soul Gold and has a shorter cd than the one from KFM. For both of them the +150% threat is perma active, though BM needs to block to be able to use it, so it may be more difficult for BM to activate it at the beginning of the fight. Since BM is build around burst damage, this won’t be much of an issue, since the damage BM can do at the beginning of a fight is very high and thus the aggro is high, too.
KFMs have far more defensive options than anything bar Blademaster, on short cooldowns
This statement is right. In terms of defensive options BM is superior to KFM. He has more resists, a block and can give the whole party a resist buff (which has a long cd). If the boss is spamming skills, then BM will be able to iframe more than KFM in the long run.
KFMs can generally hold a boss more still in one place than a Blademaster who move around a bit more, hence them being preferred as the MT (apparently?).
Both are about the same in terms of boss movement.
The big difference between KFM and BM is their utility.
BM is around party protection. They can block attacks directed at the whole part. Thus he can make the run safer and in specific dungeons increase the speed since the whole party can resist aoes and blindly damage the boss. (5sec resist for up to 3 attacks for whole party)
KFM on the other hand is about increasing the offensive power of the party. Thus they’ll increase the run speed, which is nice in all Dungeons and also the reason why KFM is preferred with Blade And Soul Power leveling. For min/maxing a KFM will be better, due to damage increase.
Though in the end it’s completly up to you which class to choose. Both are great tanks and both have their advantages. Also both of them are about as good as each other in solo play.