both eventually but I am first getting mass effect 2, the first set up a great world for which a story could be told, while the gameplay wasn't the bright spot of the game it was enjoyable enough to get through the story. and the second game looks to improve the combat, while continuing the great story.
on the other hand Mag is a fun game(played the beta for a few months), whether or not it will have legs or not remains to be seen, and being an online only game it is very important that people keep playing the game, I plan on getting it probably in the summer time, when I could get it for cheaper, if the game has a decent amount of people still playing it.