The RDA is by far the most popular system among cloud chasers. If you want to blow huge clouds, you want to be building on an RDA. With an RDA, you literally drip the liquid from a bottle into the tank via the driptip - also known as "redripping". RDAs require that you drip your juice inside, vape it off (two or three puffs), then drip some more. An additional advantage with this is that you can change up your liquids more frequently, but for some carrying around bottles may be a pain - An RTA may be a better choice.