I personally dislike any rda that relies on a side hole for air. Back in the day I didn't like 901 atomizers leaking all over everything, and don't like the Igo, or like rda's for the same reason. So I pretty much stick with the A7's that get their air from the connector.
A7 Stainless Steel Rebuildable Atomizer
A7 MINI Stainless Steel Rebuildable Atomizer Kit
A7 Stainless Steel Rebuildable Atomizer
A7 MINI Stainless Steel Rebuildable Atomizer Kit