I want to use the pie menus addon, but confusingly I have two of them. The second is called "official", and it has a higher version number, but the first one seems to have a lot more hotkeys...
EDIT As I got here only generic answers, I researched and compared them, and here is what I found: the "unofficial" 3d Viewport Pie Menus are a new addon in 2.78, and as of 2.78 they seem to be more powerful than the official ones.
- Tab: the "unofficial" is better, because it has an Edit/Object toggle, and most of the time this is what we want. One can also directly jump to the edge/face/vertex selection sub-modes from the Object mode.
- Ctrl-Space: the "unofficial" is better, because it has combined widget options
- . (pivot setting): the same
- Z (shading): the same
- Ctrl-Shift-Tab (snap): the the "unofficial" seems more powerful
- q (views): the "unofficial" is definitely more powerful, it has not only the views, but options like lock camera to view.
- Clip Editor pies: this is only in the official
- There are 11 more pie menus only in the "unofficial", all of them can be activated individually, and as the accepted answer says, one can also combine them
More information about the "unofficial": https://blenderartists.org/forum/showthread.php?401789-3d-View-Pie-Menus