It seems there's a lot of fashion in post-apocalyptic, dystopian settings for 2013, both of these and that Will Smith movie set to release. (If any of these I would expect to be awful, it's that one, for innumerable reasons.)
I expect Oblivion to be good, not great, not bad, good. Tom Cruise's niche is in the action movie genre and he's a pretty capable actor himself, but that's not to say he always aligns himself with the right projects and can be relied upon to bring us a great movie, disregarding how good he would be acting within it. I feel like Kosinski can learn from his Legacy mistakes to make a movie that's somewhat better, but I don't see him being legitimately effective enough to actually make something that will stand out, I expect this to be fun, but nothing special.
Blomkamp on the other hand, has proven himself to be capable of creating a genuine and well made expression of art and I expect his take on this style of film to be far more in line with what he's good at. Matt Damon is of course a brilliant actor and we already know he's certainly able to pull off great pieces of action-oriented work from his Bourne franchise, if there's anyone I'm expecting to take the better "job" here, it would be him. Not to mention I've always seen Jodie Foster to be a capable, rich, powerful, semi-villain and this is finally my chance to see her take that on in Elysium.
Both directors are inexperienced and their work is not substantial enough for me to really formulate an educated opinion on the director themselves. But from what each of them have made already, it seems obvious to me that District 9 would come out the better film 100% of the time. On that standing, I expect Elysium to take lead here. I expect neither to be bad, but Elysium has more going for it. Plus I think the premise sounds way cooler, so there's that.