Ok this is my 2pence worth, or your $0.2 for you
Attys, from what I have used over the time they are great to start with. But you will find yourself needing to carry arround a bottle of ejuice with you to top-em up or direct drip onto the attomizer.
Carto, Sorry I cant comment on thease as I have not really used them, but I have seen good and bad points to them.
Tanks, now your talking.. I LOVE them, makes my life so much easier to just fill my tank up (and a couple of spares with diffrent flavours) and go on my merry way. I have used the Tornado Tank system for a couple of months and its brilliant. And now I have started using a VVV device (change the voltage for different experiance) and its even better.
Also look at the DCT systems, they consist of a duel coil atty (or carto not sure on the official name) with a single hole drilled into the side and then a tank that goes over the unit with the fluid being sythened through with each puff. Again brill little things which make life easier.
Best thing to do is go with what you want, if your after a "real lookin ciggie" styled ecig, then you will be very limited but if you dont mind having something that looks like a PV rather than a ciggie then your options are far bigger.
All the best.
J