I think you could do either one and it would look great. I think it's easier to keep your wrists straight with knitting, though. More of the movement is with your shoulders and fingers while knitting, rather than your wrists. When I crochet, I twist with my hand when I'm inserting the hook into a loop and pulling it back out. I don't know if there's a way to reduce that movement.
One great thing when knitting those, is that you can alternate whether you do a knit stitch or a purl stitch in certain places, to make a pattern or picture. That might be a lot of fun for you, instead of making something plain. You could do a plain one first, to get the hang of it. When you felt more adventurous, you could try something with a little pattern. Even very simple to knit patterns can be nice.