For all my affection for Apple products, the one area in which I find them still lacking is their mouse design.
Logitech is and probably shall always be my first choice for mice. And the simpler the better; the plain ol' two-button scroll-wheel laser mouse is my all-time favorite.
I've owned a couple of others, but a mouse must first and foremost fit my hand comfortably, and the wilder the designs get (i.e., the farther from that original design they stray), the less comfortable they are for me. They're unfortunately getting damn hard to find, though.
The next best Logitech design I've found is the Logitech LX3.
I rather enjoyed the LX3 (not as much as my precious classic design, but it's largely comfortable), but it died on me recently. Well, I supposed "died" is too harsh a term, but the connection kept skipping, and a mouse is useless to me if its tracking is not consistent.
I've yet to be sold on wireless mice; the battery usage is a mild issue, more theoretical than anything else, but the biggest problem is that I don't trust the connection to be flawless. If I can run across a decently-priced Bluetooth mouse (that's not an Apple Mighty Mouse), I'll likely give it a try, but the 2.4 GHz wireless mice give me fits. I think it's a combination of the equipment around which I work constantly, and myself.
One thing that I will
never purchase again is a Microsoft mouse. Hate hate hate hate
hate them. I literally cannot stand their design. I made the mistake of purchasing one a few years ago (I never purchase a mouse in a box; I have to lay hands on it first) and I knew it wasn't terribly comfortable, but it was 4am and desperately needed and it was the only one Walmart had in stock. Big mistake, will not repeat.