I use a Microsoft Trackball Explorer on my gaming PC and a Logitech M570 everywhere else, including my gaming laptop while traveling.
My family has a history of being prone to RSI, so since 2000 I’ve used split keyboards (mostly of the MS Natural series, but now the Model 01) and trackballs (as described above) to minimize my personal wear-and-tear.
I recall that it took a little while to get used to a trackball, with a Trackball Explorer being my first one. I prefer ones with a fingertip ball to ones with a thumb ball, but I’ve used both on a daily basis for ages now and don’t have to think about it at all.
I wanted to like the Kensington Orbit because of the scroll wheels they just felt too awkward to me in practice.
Everything else aside, I love how portable the Logitech M570 is. It’s small enough that I can comfortably cup it in my hand against my leg while sitting down and use it in tight spaces (e.g. in an airport). Also, the AA battery lasts a long time (listed as 18 months).