I have a number of devices attached besides a mouse. The most important thing with a mouse is setting the response to your liking, beyond that it's just what feels comfortable - my mouse is not especially comfortable, it's a Roland sales gimmick made to look exactly like a Boss distortion foot pedal. I also use a Shuttlexpress when working with the project window though I'm now trying to get used to the CMC-TP.
What I really wanted to mention here though, because nobody seems to have mentioned using one, is a Graphic tablet. I use one of these primarily for wave editing because nothing is better for drawing than a pen on pad. These usually work in two modes, either screen mapped i.e. where you point on the tablet is always the same spot on the screen, or in mouse mode which behaves obviously like a mouse. If you get a chance, try one they're actually much more intuitive than a mouse or trackball. The only con is that if you put the pen down, you have to pick it up
but many like to keep the pen in hand if only to have something to fiddle with while listening. Actually, the tablet I have (Wacom Graphire) has a mouse as well as a pen.