Yeah, I understand that Reach is held in high regard - in this game it is actually the story that I'm interested in because it's so heavily referenced in subsequent Halo games. I know the MCC on Steam launched with Reach but I knew I would want to dive right into Halo:CE straight after.
Clearly I've lost some time as Microsoft are already upto Halo 4 in the PC series. I'm a little torn between just giving in and buying on Steam, or waiting for my Series X. In this case, I'm inclined to go Steam because I don't want a massive chunk of my Series X SSD taken up with Halo.