Banks started out on the independent circuit as Mercedes KV. It's fair to say that she didn't make a splash there. In fact she's a very good example of a wrestler who was perfectly competent on the indies but needed the finishing touches of the WWE developmental system to truly shine. In other words, she's exactly the sort of wrestler NXT and the Performance Center were designed for. Not everyone can be a Kevin Steen or a Prince Devitt.
When Banks debuted as a humble babyface she seemed promising but unspectacular. She was a good enough wrestler but she lacked the edge to make herself stand out. Thankfully she would turn heel and become a founder member of the BFFs (the Beautiful, Fierce Females) stable alongside Charlotte and Sumer Rae, a move which afforded her the chance to create a fresher, edgier character that tapped into the ever fruitful mean girls trope. It had been done before, most notably by The Beautiful People in TNA, who beat Sasha and NXT to it by a decade, but I don't think it's ever been done quite as well.
|"Bah gawd, look at the torque!"
As 'The Boss' Banks oozes superiority and confidence. She's switched to flashier ring gear, gotten herself a catchier theme tune, and taken a more ferocious approach in her matches. Her double stomp to a corner hung opponent is a simple move but looks vicious, while the Bank Statement is one of the best finishing moves anywhere in wrestling. It looks entirely convincing and Banks never fails to perform it fluidly. There is no other female performer who comes close to matching her character or in-ring prowess in NXT, and only one or two on the main roster.
Banks has worked her way to the top of the NXT women's division by wrestling well and creating a great character. She's proven herself capable of having good matches with everyone she's put against and has one of the best characters in WWE. She is perfectly positioned to become the central performer of the women's division as NXT expands. That may mean she gets slightly less money but it will also mean she gets to do more. On the main roster she'd almost certainly be relegated to a filler position for a championship that means little, if anything. In NXT she can be the perennial champion and one of the performers who helps NXT expand into something bigger than it currently is. Long term her current position is certainly the more interesting.