My personal experience.. I have a Wacom cintiq 13hd.. it doesn't get used. I don't have the desk space for it and for pixel art it doesn't really speed up my process. For Photoshop and painting it's fantastic.
I mostly use my mouse, however recently I picked up a small Wacom Intuos Comic with the wireless kit, and I find it great. The touch commands mean I can navigate Aseprite fairly easily, and being small It tucks away nicely, and with wireless I can grab it and go.
With that said though, I still use my mouse probably half the time.. I guess years of using the mouse makes it hard to shake. The Intuos is great on medium and large sized canvases though, I do feel it speed up my process there.
So mouse for things around 64*64 and under, Wacom when it's bigger, because getting curves is great.