ac+ comes with story mode and two characters who aren't tourney legal, as long as you get the american AC, it really doesn't matter unless you want the bonuses in AC+.If you're just looking to take the game seriously on a competitive level, they're both fine ports that play the same. AC+ just fixed some glitches that were in the original JAPANESE console release of ac.I'd say get plain american AC because you can probably find it for 10~15 bucks.The differences in AC+ include:Story Mode,Mission ,Mode,Extended Gallery,Kliff and Justice,Tweaked EX Characters.
