There's no such thing as "the best mouse". It's like a good pair of shoes, it might be built with quality material or look good, but if it doesn't fit your foot, it's not going to be any good to you.
When looking at a mouse, you want to find one that best suit your needs. Things you want to look for would be:
Weight(some people like a heavy mouse, others like the extremely light).
Size(this is mostly based on the size of your hands)
Shape(right/left handed/ambidextrous)
Type of grip(Palm, claw, tip)
Numbers of buttons
What makes this particular mouse good? Assuming it fits your hand and how you like your mouse to be, it has a fast wireless connection that's not any slower than a wired one(most wireless mice have additional latency), a good sensor and overall, a good build quality.
But would I buy it? No, not unless I really needed a wireless mouse. You can find a good wired mouse for less then half the price of the G-Pro.
It's the most used mouse among Overwatch pros as well.