I have mained KFM (as a tank) since the game was released here in NA/EU. I only play as a tank, and even if there's a BM in the party I will always fight them for aggro (unless it would result in a wipe for the party, like BT). The reason I do this is because most other 'tanks' in bns have no idea what tanking really means. All they really do is hold aggro, and that's it. Real tanks don't spam Q/E all over the place, real tanks control the boss and keep them facing in one direction as much as possible. Easily doable if you try. That said, let's get into facts about KFM.
First and foremost, I have always tested both builds every time our class gets a new change or a badge, and I can tell you without a doubt, Wind is by far suited for tanking. Fire sucks. And as far as dps goes for the two, Wind has been top dawg since it's buff when DT came out. If anyone tells you otherwise, they have never really tried wind, or they suck balls at it. What makes wind so much better (especially for tanking) is how fast your skills go off with animation canceling. It's very easy to sneak in lots of dps in between boss attacks, fire build cannot do this very well. Also, wind is far better at holding aggro, after the recent Threat addition to Comet Strike. Not only does Wind Comet have a higher base damage, it also can be used twice before put on cooldown. Paired with Primal Force, and you can hold aggro fairly easily. Especially during BB.
And as far as gear goes, DO NOT get Seraph. It's terrible for KFM, even with fire. I have never seen a kfm with Seraph do decent dps. Save your mats up and shoot right for Stage 4 Baleful. And try not to take advice from Fire build mains, most of them don't really know how to play kfm very well.
When tanking, keep in mind that our new Avenging Fist has an iframe, this makes it great when you have Hongmoon Elbow smash. You can block a first hit, and use avenging fist to follow up. This actually works better than the buff you get from a successful Counter. Also, Pivot Kick resists most ccs. It's hard to use at the right time, but very helpful if you want to just face tank an attack that you'd normally have to block or avoid. Try to avoid using Q/E as much as possible, as a tank it's your job to keep boss's predictable. If you're spamming Q/E, you melee dps won't be able to tell when a surprise attack is coming. Simply put, you put the effort into keeping the boss under control, and your team will kill it much faster. They won't have to worry about dodging at random times.
As for rotations, they are far more complicated than Fire, but once you take the time to master them you will always have high dps (provided bosses aren't slapping you around).
Before I begin though, one of the most important things to know about Wind KFM is proper searing palm management. Searing Palm should be thought more of as a buff, because the damage it does is not very high. Most people have no idea how to use it properly and spam it like there is no tomorrow. Simply wrong. The more frequently you use Palm, the less your overall dps will be.
Proper palm use goes like this, Fight starts > Rush to stage 2 asap > Wait till stage 2 has about 7 sec or less > Apply Stage 3 > Wait till stage 3 has about 5 sec or less > Apply Stage 4. If done correctly--combined with iframes/iron shoulders/pivot kicks/Avenging Fists for resets--by the time stage 4 ends Searing Palm's overall cd will have ended and you can proceed to rushing stage 2 and repeating.
As far as rotations go, Wind KFM isn't always about 2rf or RF spam. Your rotation changes depending on the situation you are in, your build, your team, and the boss you are facing.
My normal starting rotation for most low tier dungeons is as follows - 1 > Rmb > X (stage 1 palm) > 2rf > F > 2(anicancel) > 4 > 4 > F > 4 > X (Stage 2) > V (Tremor) > Tab (BB) > then 4 > RF > 4 > RF > 4 (till BB ends) > X (Roaring Tiger) > X > (Stage 3) > Then 2rf spam in between blocks/Iron shoulder > X (stage 4) > RF spam till stage 4 ends. Try not to forget to keep using Comet Strikes in between BB as well. Just remember, without Skyrift Mystic badge, it's easiest and faster to get your Comet off after a Pivot Kick. So Smite > Pivot Kick > Comet > Cyclone > Comet (F > 2 > 4 > 4 > F > 4) This is really great practice in general, but even better when you have primal force, to make full use of it.
Now if there's a wl in the pt, and you know they are good at popping SB early, you don't want to waste your Searing Palm. So your starter will look like this - Tab (Flying Slam) > 2RF > F > 2 (anicancel) > 4 > 4 > F > 4 > V (Tremor) > Tab (BB). This combo will put you in sync with most good WLS, you'll be able to drop Tremor right before SB (Which is what you want), and pop BB right when SB goes off.
Now this part is very important, if you don't have Skyrift, Comet is a huge waste of Dps during sb, even with a perfect rotation. Just pretend you don't even have a 4 while SB is up (without Skyrift ofc). A perfect SB rotation goes like this - X (Awakened Searing Palm) > RF spam (until SB has 7 sec left) > X (Awakened Palm) > RF Spam (Until SB has 1 second left) > X (awakened palm) one last time > RF Spam for 10 more seconds. The only reason you want to use searing palm during SB is for the 10 sec buff it grants Cyclone Kick (In short, boosts it's damage and allows it to be used freely) If done correctly, your dps will be sky high.
As for Soul Badges, I would strongly recommend Primal Force, or Holy Fire (bugged atm, doesn't work with Tremor's 20% crit damage, but still a great badge). Most will recommend Magnum cause Shiro or AALaguna does. Sure, it's an option, but it's mostly worthless to any kfm who uses searing Palm properly. The best boosts to your DPS will be Primal Force or Holy Fire. Later on you can combine the two, or combine Primal Force with Transcendence (Probably the better option).
Below is a video I did on some of the badges. Quality isn't that great (too lazy to reupload), but I left a detailed pros/cons and tips in the description. Happy Trails. Oh and my average ping is 130 - 160.