If you want something that won't leak, you could look at the Cubis tank, and it now has SS BF Notch coils available. The notch coils are made of SS, so can be used in both Power and TC modes (I know the VT doesn't have SS mode, but it can still be used in power mode). The notch coils also require less power than a standard Kanthal coil, meaning you can use these even with lower powered mods without a long ramp up time either. SS is also wonderful for Vapor and Flavor production, and coil longevity.
In contrast to the Ego One Mega, the cost for the coils is roughly the same, and the tank itself is also affordable (they're made by the same company Joyetech). here's the different coils you can get:
BFSS316 0.5ohm/0.6ohm/1.0ohm
Stainless Steel 316 (Temperature Control or Variable Wattage Mode)
BF Clapton 1.5ohm
Clapton wire offer greater surface area resulting in increased vapor production.
BF Clapton (Variable Wattage Only)
NotchCoil SS316 0.25ohm DL (Direct Lung)
Stainless Steel 316 (Temperature Control or Variable Wattage Mode)
BF Ni200 0.2ohm
BF Ni200 (Nickel Temperature Control)