For what it's worth, I have the Subtank mini, Atlantis, and Atlantis V2.
I'll agree, some Subtanks do have slight leaking issues, usually out of the airholes. I have one that leaks slightly if it gets put on its side, and one that works great.
I prefer the flavor of it over the Atlantis, though I get bigger clouds from the Atlantis.
The Atlantis V2 has better flavor and clouds than the Subtank mini.
The Subtank stock coils are horizontal, while the Atlantis' are vertical. I find the Subtank coils easier to build, but the Atlantis' easier to wick.
That being said, I have the Melo, Starre,and Matrix as well. Out of the 6 Subtanks I own, the Matrix hits the top of my favorites really easily.
Flavor kills the Atlantis V2, and cloud production is about the same at similar wattages. The Matrix can overpower the Atlantis, I've taken mine to 100w, and can give much bigger clouds, and ridiculously thick vapor while keeping the flavor up.
Side note: Stock coils are vertical, and about the same difficulty as the Atlantis.
At ~$30, I can't recommend the Matrix enough.
The Starre is a very close second. The Melo has been a bit lackluster for me.
This site has the Matrix for $25.
Matrix Sub Ohm Tank Atomizer by High Voltage