Well I guess to disect it further.
Taekwon Rankers are valuable as they have 3x the HP and SP, and have infinite combos. But thats more or less re stating what I quoted before.
Taekwons in general are good for PvP if used correctly. They can attack with multiple elements with Warm Wind. They are also party oriented for things like WoE. (See the "Fighting Chance" Skill). Flying Side Kick is also pretty useful but you'll need to practice, that goes for the infinite comboing too.
You might enjoy a Taekwon because they attack fast, seeing as they dont use weapons, and if you look further into that guide it does have some tips for being annoying in WoE.
On another note. Taekwons can be useful to farm with skills like Whirlwind Kick. But if its a really weak monster, its not going to be that helpful.
