I really enjoy the original Apple Extended Keyboard II. I'll be honest that I haven't used an actual Model M, but it's got a wonderful feel and not so horribly loud that you'll disrupt the world.
Unfortunately I've found that I hit the key rollover limit while typing certain words. For the past year I've been using one of these: https://elitekeyboards.com/products.php?sub=keyed_up_labs,te... — and while not perfect, I really do enjoy it.