Greetings from the United States.
It really is about you. Your particular needs and such. No really about brand. That said, I recommend you buy originals, and not the unbranded knockoffs, initially. If you want a vivi nova tank, make sure it is a Visions brand. If you want a ProTank, buy a Kangertech. Later you can try the other (in some cases improved) variants. For now, stick with the originals.
You say you are a heavy smoker. I recommend you skip the little cigarette-like 'electronic cigarette' and also skip the lower nicotine e-juice at first. You will need 24mg/ml or even perhaps 36mg/ml. For a device: either go with the big sharpie pen size (eGo style) or jump right into the big cigar-like 'tube mods'. The big tube mods almost invariably give you the best vapor, the longest battery life before recharge, and hold the most e-juice. If you can handle carrying one around, they are definitely the best experience. I personally recommend the Lavatube V2, the eVic, or the ProVari. Each has it's pros and cons:
Provari is very high quality (and the most expensive), but the single button adjustment is a bit of a pain to learn and use.
The eVic is very nice and is the latest and greatest (techwise). Some of the eVic features are honestly needless-but-nifty tech, but the variable wattage feature is wonderful if you want to experiment with a lot of different tanks and such.
The Lavatube V2 is a great previous generation device. It is a workhorse tube mod without any real frills except great styling.
Be sure to take a moment and read this: Five fast things every new vaper should know.
If you go with a tube mod. I would say stay away from the cartomizer-core tanks (tank around a metal tube with fiberfill and an atomizer inside). I recommend you buy both a few Visions Vivi Nova tanks and a few Kangertech ProTanks (get the new version with the base-breakage problem fixed). As with the battery devices above, each has it's pros and cons. Trying both will tell you which you prefer.
Visions Vivi Nova is a top wick/atomizer tank. Kangertech ProTanks are bottom wick/atomizer. Both make great vapor, if used right.
Feel free to ask for any other help. I wish you good health and good fortune. Happy Vaping!