Can you increase your budget a little bit. I have two amazing options for you. Number one is a Subtank Mini or Nano(18mm), they shine around 25-28W with the sub ohm coil and really sing around 15-18W with the 1.2 I have found, they have amazing flavor for a clearo (going to blow your aero tank out of the watter,) you can vape em with thick thick juice chain style and not get a dry hit AND the best part IMO is it comes with a RTA (rebuildable tank atomizer) head so if you want to go that route you can but don't have to. It chucks pretty nice clouds, conserves juice quite well for a sub ohm setup and the flavor is damn good with the prebuilt heads which to top it off are straight up organic cotton and that's all. Now number two is the Joytech Delta II, it shines around 40-50W IMO but I do vape it much higher on occasion, it CHUCKS clouds and IMO the flavor is a bit better then the sub tank but that could be just due to the fact I prefer a warmer vape and the Delta II offers that at 55-70W where as the Subtank will just taste dry and burnt that high (not a bad thing though as it vapes amazing at a lower wattage) and it has an option for a RTA head as well.
Overall I like the Delta II better and that has been the same opinion of everyone down at my local vape shop I let try it (a week latter my group of guys I hang out with down there all got em on there devices lol.) This thing really chucks the clouds I mean much more then the Atlantis, Melo and Subtank and as I said I would give the edge to flavor to the Delta II. The Subtank is really an exceptional clearo though and it really depends how you want to vape. For example my roommate actually finally quit smoking with a Subtank (.5 ohm pre built coils) at 25W. He doesn't like the "warmth and density" of the vape from the Delta II at 40W+ nearly as much as he enjoys the cool tuned down vape of the Sub. This is not to say the Sub doesn't put out clouds cause even at 25W it chucks enough for me but again for my own personal reasons I like the Delta II. Tell me about your style of vapeing and I can offer an opinion on which one to get.
The thing is though, you are going to need a device that fires sub ohm unless you use the 1.2 ohm coils in the Subtank which still work really well. I wouldn't really recommend a Nautilus anymore or the likes (aerotank, silo etc etc) just because the Sub has some serious flavor and doesn't need to be run at sub ohm resistance in crazy high wattage. As stated I set my roommate up with a Clopour Mini and a Subtank at 25W and after trying countless Ego style batteries, a Vamo with a Naitilus, a Silo tank on an I Stick and a few other setups he hasn't touched a smoke in days and doesn't care to.
Edit: In comparison with at Atlantis the Sub has sooo much better flavor as does the Delta II, please don't let your bad experience with an Aerotank limit you from buying a Subtank because there really extremely different and Kanger really hit this one out of the park. The Atlantis was an amazing clearo when it dropped because there was nothing else out like it but IMO the flavor is really, really lacking on the Atlantis. I mean I NEVER use it anymore, all my love goes to the Subtank Minis, Nanos and Delta IIs I own. Well, for clearos at least.