Comparison of trackballs.
Logitech's M570 trackball is the most popular, simply because of the name. Whether you like it depends on whether you like thumb operated trackball.
See video reviews at Logitech M570 Wireless Trackball
Not so good. Small. The scroll touch ring doesn't work so well. But if you need a portable trackball, this fits the bill.
Detail ＆ video at Kensington Orbit wireless trackball
This one is from Japan. Not much reviews about it.
this one is well-loved. Medium sized ball, only 2 buttons, medium priced, but best thing is the scroll ring.
detail ＆ video at Kensington Orbit Trackball with Scroll Ring
The Logitech Trackman Marble is a classic. Loved by 3D software users (Computer Aided Design). Common complaint is that it doesn't have scroll wheel. Best thing is the ball here, which can spin.
See video reviews at Logitech Trackman Marble Mouse
Best design. 4 buttons. Huge ball. But there are complaints about the software. No scroll wheel.
for video, see: Slimblade Trackball
see also: Slimblade vs L-Trac Trackball.
Classic. Huge ball. 4 buttons. Best thing is scroll-ring. But this is large, and tall.
more photos at Kensington Expert Mouse
Highest quality. Biggest of them all in size. Huge ball. Smooth scroll wheel, plus 3 buttons. Expensive. Minor complaints is that the scroll-wheel and middle button are hard to reach, and isn't as ergonomic.
See: Slimblade vs L-Trac Trackball.
This is $25. From the looks, it seems to be a fantastic one. But bad reviews. No scroll wheel. 2 buttons only.
This one just remindes me of Star Trek. Some people on YouTube modified it so the ball lights up.
The best trackball ever, ever, is the Microsoft Trackball Explorer. (discontinued) For detail, see: Microsoft Trackball Explorer.
Trackball have some advantages over mouse. Here's a summary of the reasons:
If you read many user comments on amazon, you'll see that many 3D Modeler users, or persons with mouse-induced RSI, even some gamers, swear by trackball over mouse. 〔➤ Celebrity Programers with RSI (Repetitive Strain Injury)〕
Here's other claims about trackball, but am not sure.
I think trackball and mouse are just different. They have different characteristics. One advantage of mouse is that you can use it for casual drawing, because the way mouse operatos is somewhat like a pen — you move it and it leaves a trace. Drawing with a trackball is difficult. But if you really need to draw, a pen-input is much better. 〔➤ Jog/Shuttle, Touchpad, Cyborg Mouse, Pen Tablet〕
One of the most attractive quality of a good trackball is that the ball spins, with mininum amount of friction. You can try to spin the ball. If the ball kept spinning for a second or two, it's GOOD.
Of the trackballs that i know for sure spins, are: Logitech Trackman Marble Mouse, Slimblade vs L-Trac Trackball, Microsoft Trackball Explorer.
A veteran trackball user ( nsrpgmiv ), who has owned many different models of trackballs, made a comment that i think is very insightful and i agree with much. He pointed out that trackballs designed for the long fingers is much easier to operate than the thumb. This you can easily test yourself. With thumb operated ball, it assumes your palm sits still, thus your thumb movement are limited. In particular, going up and down is of limited range. With index finger operated ball, you can spin it easily, side ways, or up down. Your hand can easily hover over the ball freely. For him, he preferred the Logitech Marble than the Trackman Wheel.
Most comments about trackball are simply about how it is better than mouse, but is not actual review about a particular trackball product in comparison to other trackballs.
Unlike mouses, different design of trackballs have different ways of operation. One of the major difference is the ball size. Some design have you use thumb for the ball, others you use your middle finger or index finger to move the ball. The placement of ball also changes the location of all the buttons.
If you have RSI and don't like trackball, you might try some ergonomic mouse, or trackpad, or some fancy input devices.