My running club, had quite a heated and exciting debate this week!
All the experienced marathon runners, like myself, wear their watch with the face on the inside of the wrist. This means with even the tiniest of inflection, data fields can be observed easily while running at pace. Wrist based HR monitors are massively more accurate too.
Checking a watch face the traditional way up is not advised as it can't be achieved while running at pace without breaking form/arm carriage, and awkward arm movements.
Opinions? I've worn my watch this way for years, as Kenyans do.
Some disagreed, but they were slower runners/joggers.