I personally , like my Reo Grand , it's a bottom feeder , that holds 6 ml. of juice , doesn't leak , and can use different batteries , for 3.7 , 5 and 6 volt vaping . The best part , for me , it's all mechanical , so I don't worry about anything shorting out , or failing . I just need fresh batteries , and I'm good to go . Ce2's and tanks , map tanks , etc , all will leak , on occasion , and IMO are a lot more work , than I'm not willing to expend .