>>1
I use the standard scroll-wheel ball mice, either PS2 or USB connectors. Occasionally I end up on a friend's computer with an optical mouse, with no discernible difference. Since I haven't paid for a mouse in many years, I use whatever is available. On another friend's computer, he uses a non-scroll-wheeled ball mouse through a serial port (9-pin D-sub connector). Other than missing the scroll wheel, there's again no discernible difference.
Occasionally my home mouse picks enough dust, lint, cat hair and skin oil to form a line of compressed dirt around one or both of the rollers inside the mouse that the ball rotates against. The dirt tends to make the ball slide against the roller, so the cursor slips equally on the screen. I pop out the ball, scrape off the line of dirt with a fingernail, and after a minute or so the mouse is clean enough to use for another 4 weeks before I notice slippage again. An optical mouse doesn't have that much of a problem with dirt ... although I have seen them clog up with hair, which affected the tracking similarly. It seems that an optical mouse simply suffers from clogging at much less of a frequency than the ball mice.