Good thing we don't have to choose only one, but I'll play.
I can get a good dive watch from many other brands, although I love my Ti Planet Ocean 9300 the most which I wear about 6 out of 7 days a week. But the Speedmaster Pro Moonwatch is an Omega exclusive, so it would have to be some form of the Speedy Pro. Picking which Speedy is the harder part.
I love my 3572.50 with Hesalite crystal and sapphire caseback, which looks like the traditional moonwatch from the front, but with 50M WR, Superluminova dial, and a beautiful movement seen through the display caseback. Vintage doesn't have as much draw to me, because I want my watch to be a GADA (go anywhere do anything), so it will get wet and need to tell me the time in the dark.
But my favorite Speedy dials are reverse panda's like my ST1 or a Speedyorite (Apollo Soyuz Meteorite), but also the brilliant white dials of the Silver Snoopy Award and the Alaska Project dials appeal to me too (more than the creme colored white Italina dial, but less than the panda). So, my ST1 would more likely survive the cut if I had to sell everything else.
Given free will, I would not pick a Daytona over a Speedy, and I would not pick a Submariner over my Planet Oceans. But the Rolex are watches I like to add to the rotation.