Too many people here are basing their decisions on netcode. MK has a horrible netcode, yet the people that complain about it still play frequently online. I believe the same will happen with Injustice.
Personally, I haven't really played MK in months. I do miss playing it, but everytime I put the game in I become disappointed with all of the issues in the game. It's sad because I grew up with MK and love the franchise, but I'm sick of bugs, glitches, gameplay mechanic issues, etc. etc. I'm a big Batman and FG game. NRS seems to have addressed the major issues I had with MK9 for Injustice. If the game plays as good as it looks so far, I doubt I'll touch MK except every now and then.
I don't want this website to turn into a MK vs. Injustice fest though. Both games are produced by NRS, I don't see why we can't support both games like the Capcom community does there's. Lets just remember this because I can imagine a lot of bitching about news/posts when Injustice drops. MK only guys will be salty.