Rattlehead i found with the regular tfv4 tank even with the stock coils you have to leave a pocket of air in the tank when filling. As far as vapor and flavor production, with the tri coil i found they dont really produce until around 80w and up. But this is from my experience.
Kanger makes very reliable stuff everything from the T3 to the Subtanks, probably your best bet would be a Subox mini kit, that way your girlfriend won't want it (box mod).