As a hardcore trackball user for the last 20 years, I avoided using mouses unless I had no option. Recently I have tried Logitech G700s, Roccat Tyon and G403. Recently I just discovered the Swiftpoint Z and loved it.
The main features that mattered to me are:
It is the only mouse I know of in which you can access 8 of the many buttons with just the index and middle finger. All the mouses have their extra buttons on the edges and require stretching fingers laterally to reach them most of the time.
The button programming are deep and intuitive. Love how I can configure any keys and buttons in variety of ways. Awesome that its compatible with XIM Apex
The vibration/rumble effects lets me know if I activated a button. Being able to set a different dpi to x and y axis is useful.
Info display lets me know the status of my mouse such as which profile I'm using, what dpi I am at etc..
And I haven't even delved into the analog and tilt options
This is now my favorite mouse will be for a long time unless they make a Z 2.0