The ones I enjoyed the whole pre-order process for were WoW's TBC and WotLK. But they did have install time and server issues at launch.

It was fun overall but I remember waiting for a server queue only to see a huge mass of people in the starting areas, waiting for quest mobs to respawn to race to get the first hit on and the relief that came with finally getting ahead of that pack. They didn't have digital versions despite the game being completely online and blizzard probably being one of the few that had the bandwidth available to run an online store at the time.