Budokai 3 really is the best that it was and probably ever will be in terms of a game but I'd also recommend Burst Limit. That game takes the systems of Budokai and refines it, it's has (in my opinion) the deepest fighting system of all the games. It doesn't go past the Cell saga and you can probably find it for $5 used at a GameStop.
Whatever you decide on though, avoid Ultimate Tenkaichi like it's the plague.