Ive been wearing my MO on Stowa's grey croc until very recently when I put this on it, not exactly the most expensive strap out there though it works perfectly IMO. A grey NATO or perlon would work well, as might burgundy or beige/lighter shade of brown - anything that'll contrast against the blued handset should be good.
https://www.watchobsession.co.uk/col...-in-gold-brown