Just depends upon what looks good to you and how much do you want to fiddle with your delivery device.
The string-wicked clearotanks such as the Vivi Nova and Kanger Protank and the like are the simplist to use. Just remove a part, drop your liquid in, and you are good to go. They are somewhat position dependent, as you need to tilt the device to keep the string wicks wet to avoid dry hits.
Cartotanks have a slightly higher learning curve. Not position dependent. Success depends upon learning to pre-fill the carto adequately, assembling/filling the carto/tank correctly, and possibly adjusting your vaping technique slightly to allow the juice from the tank time to refill the carto.
RBA's have a higher learning curve. Success will depend upon learning to roll stainless steel mesh into a skinny wick and learning to wrap a coil to a specific resistance range. Some degree of beginner frustration should be expected at first, and a backup juice delivery system should already be in place before attempting an RBA, in my opinion. These are rather small parts to work with and the user should be willing to be a "tinkerer" type person.
You provided no background information on how experienced you are, what delivery devices you've used before or are now using, or how adventurous you are (speaking about RBA's).
