Hi there!
I have both the tanks and cartomizers, so I'll talk to those.
Tanks can be reused -- just pop the top, wash it out, and refill. The hole does get torn a bit after a while, but there are replacement caps you can get for like 39 cents.
I personally prefer cartomizers. These are atomizers and cartridges built into one unit. That's nice because they're like $6-$8 for a pack of five, so if they last a while, great, but if they don't, it's no big loss. I fill up a couple of cartomizers with different flavors and nic strengths (like a tobacco/coffee blend at 18mg in the morning, a green tea 12mg during the day, and 8mg tobacco flavor at night). Very customizable and less messy than using atomizers and cartridges separately.
I really like Boge 510 LR (2.0 ohm) cartomizers. I'd recommend you get that starter kit plus a box or two of cartomizers, so you can try both methods. Make sure you get some 5ml samplers of different e-liquid flavors, too! Buy from one of the links posted above, and you'll probably save enough money to add cartomizers and some juice for what you would have paid from the other place.