I would look at an Aspire Atlantis Version 2. If you are going to use it on the Testla Invader box, you will need to get 0.3 Ohm organic cotton coil heads for it, I'd buy a box of 5 for spares. The 0.3 Ohm coil head will give you quite a bit of vapor with the Atlantis V2. Since the Tesla Invader 2 is a semi mechanical box mod (meaning no way to control voltage or wattage), you control the resistance of your coil heads to either get more vapor with a low Ohm coil like the 0.3, or less vapor with the 0.5 Ohm coil head. The 1.2 Ohm coil head is not really useable with the Invader 2.
You need to understand that sub ohm tanks by their design create a lot of vapor. Probably 8-10 times more than an Ego twist with a tank. Therefore, you will need to purchase eliquid at a lower level of nicotine than you use currently. If you use 12 mg, you should by 9mg, if you use 6mg, then buy 3 mg.
The reason I recommend the Aspire Atlantis 2 is because you have 3 options for coil head resistance instead of 2 with the Kanger Sub Tanks. That, and I own an Atlantis V1 and V2 and think they are truely great sub tanks for the money.
If you want to drip, then you will need to learn how to coil and wick a rebuild-able dripping atomizer (RDA). I suggest a RDA called the Steamboat V2. It's easy to build on and is less than $20. If you go the route of rebuilding, you will need to do a bit of research before embarking on the journey, buy a good Ohmmeter to check the resistances of your builds.
Hope this helps.