- Based on Facebook data: Guild Wars 2 has ~1,000,000 likes. Elder Scrolls Online has ~1,600,000.
- GW2 has been out for almost 2 years.
- ESO is in closed beta.
- ESO attracts users from multiple platforms.
- GW2 is a sequel to a existing franchise. GW1 sold ~7,000,000 copies. GW2 has sold ~3,500,000.
- ESO is part of an existing franchise. Skyrim has sold ~11,000,000. I cant find accurate numbers for Oblivion or Marrowind.

Guild Wars has respectable numbers but Elder Scrolls is clearly the more popular franchise.
But does that really matter?
Bethesda is going into uncharted territory by making an MMO. There's no guarantee it will translate well.