I've never worked in pastel pencil before, but if it looks anything like regular pastel, I'd default to watercolor. That just my medium of choice between those two options.Maybe you should decide which you like better or which one you think will give you better results. Or you know what! Do a little color study for both and see which you like the look of better.
well i mean i've worked with both extensively already but i'm trying to decide what would look more convincing for this particular character