I've tried TC with Ni200, Titanium, and Stainless wire. Out of all the order of best performance and flavor for my tastes were Stainless, then Ni200, and dead last was Titanium (I barely get any flavor with Ti wire for some reason and I've tried every trick in the book building my own, on top of every prefab Ti coil out there, just way to muted for me). Its a trial and error, where I first started there was just basic guidance and very few options on the market as far as gear, first years I suffered through buying this and that until I learned what works for me and what does not, compared to nowadays with the plethora of devices available. I work in a vape shop so even have to tell customers, I can give a general path and description to help them but in the end, everyone's tastes are different, with Variable Voltage/Wattage/Temperature that variable opens up a whole host of notches but best path is start at lowest settings and gradually work your way up.
Leaking issues, yes every tank and atomizer has its issues, fully sealed units would be less issue for leaking, but we have found open/adjustable/rebuildables and host of others work best tbh, once liquid is added to the mix eventually leaking is bound to happen, nature of the beast. Due to my experience, what I call leaking is different than someone just getting into this, to me leaking is literally, get done setting up a device/tank, sit is aside for a few and come back the whole tank is empty and juice all down the mod and on the desk, where condensation collecting in contacts and airholes it is condensation that has drained or accumulated over time due to heating and cooling compounded by humidity. Flooding, there in comes bad seals, barometric pressure increase and decrease, there are a whole host of variables, you just have to learn to troubleshoot them and adjust or fix them. The Kanger Subtank/Toptank line can have its leaking issues due to manufacturer defect (seal tolerances etc, being Kanger mass produces these, more defects will appear), thus far the 2 Subtank plus tanks I own have no leaking issues unless I built the coils or wicked them wrong, the Toptank Mini I have came with a kit and it leaked like a siv until I replaced the seals with much tighter ones. Personal vaporizers are not as plug and play as many try to portray in my experience, all of them require maintenance and upkeep with the occassional troubleshooting and repair a problem if you can, they are electronic devices after all that handle liquids.
The devices you had before you are probably now seeing with a much more powerful device output wise and configurable wise, there is a vast difference, even among same manufacturer, the Kbox mini (Sub-box and Top-box Mini mod itself) is a pretty powerful little mod (50watts Sub-box, 75watts Top-box version), with a higher ramp up power you will heat things up real quickly compared to say in comparison the Top-vod you previously used, 3.7v nominal voltage on the Topvod compared to a mod that can spike initial ramp up to 6volts is almost plus 2/3 the normal output you are used to, so bring down the settings a bit. I also own an Evic VTC Mini myself, and side by side next to the Kbox Mini V2 (top-box version), the extra ability to adjust not only my TC settings but my max wattage on the VTC Mini, I prefer the Evic more in TC mode than the Kbox, straight wattage mode, the Kbox performs better than the VTC Mini. No Kanger does not produce any Titanium Coil heads that I know of, Joyetech does and you might find them for the tank that comes with it be an Ego Mega One, Tron S Tank, Cubis, etc, so you might actually like the Evic better, in that case still keep the Kanger as your fall to backup mod.
Adding correction to
@Hitmetwice 1.0ohm is not sub-ohm, 0.99 and below is Sub-ohm (aka below an Ohm), 0.3 to 0.2 is super-sub-ohm, making 0.15ohm extreme-sub-ohm (Ni200 though the range for TC on most mods is 0.05 to 0.5 with Ni200, but to get a 0.5ohm Ni200 single coil mass of wire is just to great and the performance would be anemic, so 0.15 to 0.2 with Ni200 is really the narrow window for best performance)