Personal preference plays a big part in anyone's liking for a particular
mod. Not everybody likes that sort of button placement, but personally I love it

I don't activate with my fingers, though, I hold the
mod with the button against my hand and then activate it by squeezing the tube into my palm. I find it to be a very comfortable arrangement, both for my GGTS and my Xhaler
On the flipside, I've owned a Notcigs mod and would never hesitate to recommend them to anyone, they are
excellent devices. If you want VV with on-the-fly adjustment, then that is the way to go
Maybe none of that helps you in your decision, but in the end you just have to weigh the features of each and decide what works best for you
EDIT: and tanks will look about the same on either the Buzz or Xhaler. The size and form factor is very similar, as is the height of the connector (referring to the 510 models)