I have 2 standard size DIDs, a GP Spheriod and a RSST that I use daily. I love the spheroid because it's so portable, I don't have to worry about keeping it upright or what position the wick is in when I
vape. It gives good flavor and performance but not quite as good as my gennys. I love my DIDs for the same reason Rule stated above, no worries that the top cap will come off. The RSST performs just as good as my DIDs and costs almost $100 less, the top cap is nice and snug and I don't worry about it coming off.. because of the washer/spring and insulated wick hole.. it's easier to get setup and running than the DIDs. I do love my DIDs and really have no problems getting them recoiled, they're just not as easy as the rsst.
I had a zap but traded it for the spheroid. It was nice and worked well but it was heavy and the top cap was a bit too unstable to take out and about.