Both are good and offer very similar performance across the range they offer... it kinda does come down to personal preference and price. I personnaly prefer the kanger tech devices, currently using an aerotank v2. I hate the stock coils for it though, every one I got seemed te be crap. I now use it with the nature cape coil and its flawless.
My friend uses an aspire tank the equivalent to mine (I forget the name, the Atlantis?) and the standard coils are really good when I've used it, he gets a fair bit of life from them as well.
But of course then there's people who have been fine with kanger coils and not with aspire. Its all makes your question hard to answer really.