The 2.0 rebuild kit has better armor sculpt than the 1.0 version (among other benefits which you can read about here).
Within Bandai, you have 2 choices:
- Old school Eva 01 (from the TV series and End of Evangelion)
- New Eva 01 (from the Rebuild series)
Although everyone has different opinions, the general consensus is that the new, Rebuild version Eva 01 kits are higher quality in almost every area that matters (i.e. joint articulation, freedom of movement, decals, accessories, posability, proportions, detail, and color separation). The new kits also have a rubber elbow joint and the chain gun that was used by Eva 01 in the first movie.