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.