Right now a wired Logitech RX1500, largely because it was very inexpensive after a rebate but I'm not all that picky if it meets the following requirements:
- Fairly lightweight - This rules out cordless unless it can run from 1 x AAA cell which some can, even if they have a 2 battery chamber they run the two cells in parallel, and even if it's a AA chamber, I can put a metal shim in to bridge the length difference between AA and AAA. Similarly on wired mice that have a weight in them, I take the weight out.
- Smallish size. I don't have small hands but move mice with finger motions, minimal wrist and no arm movement. Maybe someday if I get arthritis I'll want an integrated trackball but for now I don't, have one and prefer a smaller lighter mouse without it.
- Laser - I've tried many non-laser making the claim they equal laser performance but don't, especially if cordless that's optimized for low power consumption, or used on a variety of surfaces instead of some "ideal" mouse pad.
- Ambidextrous, or at least the casing shape is. I'm left handed, but also adept at using right hand because it's a right handed world, but want the choice.
- Logitech - I don't need fancy but I want good tracking and a solid case fit and finish. Anything else that equals Logitech in these regards tends to cost more, or is a gamble. I've returned mice for no other reason than "looks and feels like junk".
One of my favorite mice that fulfills all the above is a Logitech MX300, but it has only two (plus an awkward to reach little middle 3rd) buttons and no freewheeling wheel feature.
