To be honest, the red background with the black text/info is a little hard to read.
That being said, like phantasico I’m partial to black/red combos.. more bold color combinations. Keep a list of colors you like in a file for future use (or you can make your own color themed collection later on)
What I’d suggest is the following:
There’s two links to color scheme generators that will help you find colors that complement/contrast well.. find a combination you like and test it out in the editor. Send it to your watch and see how it looks when shrunk down to watch size.
EDIT: I like that shade of blue in the 2nd watch. I’d put that color into the link above and see what they recommend looks good with it.