AeroTank. No leaks, no gurgles. The coil head is isolated from the battery pin so no liquid remnants on your battery pin when you change the head. I would assume that a mini AeroTank would have the same build in a smaller body. I am on the fence with the Nautilus. There are many users, but I keep seeing negative reviews.
Quite honestly if you change flavors like I do it may be a good idea to get a handful of T3S or EVODs. Most Kanger bottom coil units are alike and the body is the main difference. In my EVODs I usually put tester juice to see how it is. Once I find an ADV I usually put it in my T3S (more capacity) or if I consider it "premium" it goes in the AeroTank. I don't have much gear but that is what makes me happy. I must say that ditching the stock silica wicks and slipping in some organic cotton into the factory Kanger heads has made a WORLD of difference to me. No gurgles, no leaks, just pure vaping pleasure.
I plan on getting a handful of EVODs as they have a smaller capacity and I can switch the wicks for another liqud once I run it dry if I feel the need. Personally I like to keep 3-4 flavors on hand just to mix it up a bit, and not to kill a flavor that I really like. To me it keeps the vape buds alive.