Back when Fujifilm X-Photographer Michael Schaake was also a Nikon user, he used to take part in workshops for photographing dogs in action with the X-T1 and D750. As he states in his article, he achieved very different results with the two brands:
I had the X-T1 and the D750 with me. The X-T1 gave me around 45% in focus shots while the Nikon D750 gave me around 65%.
Curious to find out just how much better the continuous autofocus algorithm is compared to the previous generation of Fujifilm cameras, he decided to use a pre-production Fujifilm X-T2 for the same genre.
For his test, he photographed a black labrador running toward him using the small zone focus AF mode, burst speeds of either 11 fps or 5 fps with live view, and the various new C-AF modes. Even though the firmware is still beta, he found that the results were comparable to those he achieved with the D750.
You can read the full article and see lots of sample images here!