I love the dial and case of the Seiko, and it's probably the better diver of the two - but I've had a few of them over the years and just couldn't click with any of them. I still have a few Seiko watches, but no MM300, whereas I have a number of Black Bays, including the earlier ETA and in-house.
So... i would pick the Tudor. but I'd prefer the older style bracelet on the current in-house watch. I think I'll put one of my Harrods versions on the older bracelet, as I already have one of my black ETA's on the Ranger style bracelet, the same as the one of the one watch Black bay with straight hands:
https://monochrome-watches.com/uniqu...w-live-photos/