Probably the one that gives me the most replay while also releasing early enough to justify waiting for it.
Destiny is up there, but it does release in late 2014. Elder Scrolls Online also has a ton of replay value, and it comes out in June. That puts it above Destiny. Titanfall is the last one I can think of that has a good replay value, and that one gets released the earliest. However I dont see it having that much replay value (not for me at least) compared to the others. Id say my choice would have to be Elder Scrolls Online.