Live's animations still look incredibly stiff and awkward. The bodies as well. It's rather amazing how weird it has looked all through its recent failings (trying to be NBA Elite, etc).
Until they prove otherwise it's 2K. I think that series just gets better with each game and right now is the best sports game franchise. There are still issues but the core gameplay is so solid in 2K13.
Probably my biggest issues are just graphics and atmosphere with 2K and it seems like that is a focus with how they've shown facial animations and that kind of thing.
Even if LIVE managed to provide good gameplay (which is far from a given) they'd have to match 2K's feature set (Deep Association mode, all the classic players and teams, My Player, etc) and that probably won't happen. All of that is very key to me because I heavily use all those features. I play 2K now by doing a fantasy assosciation draft with all the best current and classic players mixed in together (so I have a team with Pete Maravich, in his prime KG, Alonzo Morning for example).
Really looking forward to the next gen versions of 2K. I play on PC so it'll be nice to have a version that looks better and takes more advantage of that power.
I just wish EA would bow out of the basketball sim market and go back to making NBA Street games.