“It looks like you’re working out,” the watch face reads. That’s followed by a big, yellow button, suggesting I start an indoor run. I tap the neon button and the clock starts, comping me a reasonable approximation of the time it took for the Watch to be sure what sort of activity it was detecting.

If you take a look at the smartwatch market, Apple and Samsung are currently the two manufacturers that stand out most from the crowd. And it's exactly these two that have now launched new models, the Watch Series 4 and the Galaxy Watch, respectively, which of course are supposed to be better than...