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It's not popular, but I quite like the Kensington Expert Mouse trackball.

BTW, ignore the newer model (the "slimblade" or whatever); for reasons no one can explain, Kensington made the top two buttons on it not HID buttons, but special magic cookies that only their software can use, which is annoying.
 
For portability and versatility I would go with the Razer Orochi. It can run off of battery power or plug in via micro usb, and its BT so its perfect for MacBooks.

At home I use the Mac edition of the Razer Death Adder though. Most comfortable mouse ever.
 
Second the Razer Deathadder.
It is a really good mouse and the extra buttons are placed so you can easily use em.
 
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