Maybe its just that I'm a huge fan of both the gundam series and 2-D fighters, but I myself find that Gundam Battle Assault 2 is the best Gundam Game to have ever been released(I admit I haven't played Gundam Musou yet). It combined so many of the Gundam series into just one game, had a huge slelction of playable characters, and it follows the classic 2-D stlye of using quarter cricle and half circle moves which allows it to flow very well. The only thing I can find wrong with it is that I wish every character had a motto to yell out when they used their special moves.
My only problem with battle assualt three is that I don't know just how well it transends into the 3-D world. We all have played 2-D fighters and know that there are some that just didn't make a good transfer to 3-D. ex. King of Fighters
"You will only have eyes for Me!"