My experience (so far) I like either a 555 or RY4 throughout the day in 18 mg.. in the evening I switch to either clove or almond Joy believe it or not ;0) or some other different flavor like orange crush in 24 mg strength.. even though 555 and RY4 are in the tobacco branch of the juice tree, they are different and more mellow then the strait up Marlboro clones.. I use jumbo cartos from Nhaler and they last quite a long time before top off as they hold 2 ml in the initial fill and top off with about 3/4 ml.. I am not a chain vapor so these last about 1/2 day before top off.. I also use their drip-o-mizers which are easy to top off.. Juices come from BWB, FSUSA, and E Liquid Planet.. all made in the USA.. I also like the V4L WOW cartos