TERA is generic korean classic with a new combat system. If you like the kMMORPG methodology TERA is great. Guild Wars 2 is "newage" MMORPG ideals, wrapped around a more fluid slow paced less dynamic combat system.
The thing that got me about guild wars 2 is got to level 80 quickly got geared up, and then i found myself saying "well now what...?"
The living story doesn't cater very well to those who want a contiueous MMORPG experience. Guild Wars 2 feels like a kinda like single player RPG thats online...kinda hard to explain.
TERA however plays better into an actual mmorpg experience because well its pretty much a classic korean mmo kill this get this kill this get this go hub to hub, grats youre max level now kill other people with said character. Although open world PK is the shit in TERA. I freaking love PKing Elin players.
TERA offers a more contiued game play experience, Guild Wars 2 is more rich and varietised and its core PVP mode is more like a MOBA than it really is an actual PVP mode for the game. which i felt was really dumb of them to do.
TERA is korean, so you have all your little korean ideaologies in it, like lots of vanity items hard work equals good gear, Teir scaling gear ect.
Guild Wars 2 is worth it for a play through, but unfortunately its one of those "was fun while it lasted" things.
Which is sad, i wish i could play my norn more often but theres literally next to nothing fun to do in game anymore.