I've played other MMOs - World of Warcraft for 10 years, Final Fantasy, Wildstar. They're good in their own ways.
But Guild Wars 2 takes what other MMOs have done and vastly improves them. Immersive story, beautiful graphics, fluid and fun combat with versatility. There are no standard cookie cutter classes e.g. healer, tank.
Don't want to raid? Don't. Don't want to do dungeons? Don't. There is no 'right' way to play GW2 and that's the beauty of it.
Each player/character is completely unique not only cosmetically but build-wise.
There is no grinding!!!! It doesn't feel like 'work' like other MMOs and there are no stupid, miscellaneous quests like 'collect 10 meat'. You can deposit crafting materials from your bags to your bank without visiting the bank so you have more bag space.
All of the mistakes the others MMOs have made, GW2 fixes. AND THERE'S NO SUBSCRIPTION.
10/10 I'm happily obsessed and heartily recommend this as the best MMO ever.