Tough call. When my hands are sweaty, especially if I've been drinking electrolytes, I get a lot of touchscreen glitches with my phones and other touchscreen devices. Makes it tricky to use the two-finger or three-finger options to zoom in/out with maps, or snap a screenshot.

My bike computer is pretty simple, GPS but no navigation aids or maps. It's strictly button-operated. If I did use a full featured navigation computer I'd prefer it retained at least some button controls in case I couldn't operate the touchscreen with sweaty mitts.