That I can just run around and kill shit, I love the feel of the combat and the crucible is so fun, but nothing beats the strikes and story missions with 2 or 3 other buddies, corresponding and working together. I love the classes and their abilities. I love the weapons and how you have to earn them in PVE to use them in PVP. The fact that snipers, shotguns, and fusions are secondaries is awesome. But probably most importantly, I love how it hooked me in and its so easy to pick up on. Unlike warframe. I tried it, and it was okay, but then TONS of dlc for it came that costed way to much and I didnt want to pay tons for a game thats not that fun to play for me