If your budget allows I would go with a Bliss...I didnt have much fun with a ZAP and always got a dry spot leading to a hot spot. It could be my wick job but I have done several with success but not with a ZAP.
However I think if your into getting a RBA and dont want to invest too much on it. You should consider a RSST. I use that as my all day vape and my vapor production is alot, comparable to my dual wick nimbus.