I would recommend a GoGo from Nhaler.com it's about the size of a cigar. The battery stays charged for a long time. As a matter of fact i have used mine for the past 20 hours and haven't had to charge it. (speaking of which, i need to goto bed

). The cartos i am using have lasted 3 weeks. I just keep topping them off. The only down side I have seen is they are boring to maintain but they hold 2.8ml or more, maybe 3ml at a time.
Some people have problems with the battery making connection with the cartos/charger so that would be a risk you would be taking. But when it works, it works great and mine has always worked.
I have had NJOY, Prosmoke, EGO and now the GoGo. The EGO, I used clearomizers but I always had wicking problems depending on the juice. I was going to go with the EGO-T until i seen reviews of the GoGo. The main downside i see with the GoGo is since the cartos holds so much juice, I find it hard to sample juices without wasting 3ml of it.
So if you are fairly set on the juice your going to use, I would go with it.