It's simple, VF4Evolution is the best PS2 brawler, period. Tekken, Soul calibur, and DOA aren't even on the same league.
VF4: Evo improved every aspect that made VF4 great.
The Graphics are sharper and more detailed. The Music, well, its average at best but who cares, when you have such a strong and deep gameplay, presentation is not that important, besides it only lacks in the audio department.
The gameplay has always been and always will be VF strong point. It's the case of gameplay over glamour, and hell, just mastering the general gameplay mechanics can get years out of your miserable existence.
The rock-paper-scissors mechanics, the juggle combos, the floor impact recovery, the extremely well put side step (please namco, take note on this). Every character is a monster with a huge array of attacks and possible combinations, every character in this game is more complex that the entire DOA cast. And besides all that, the game is extremely well balanced (again, namco take note on that). The AI has been revamped, and now uses real player's patterns. The AI improvement surely shows as you advance in Quest Mode, every arcade is more challenging than the one before, and completing Quest with every character is a test of endurance that the average player is not willing to put himself into.
Even if you complete this and you believe that you have mastered every character in the game, you are wrong!!!!, dead wrong!!!!.... It can take you a lifetime to truly master any VF character, especially some of the advance characters (Akira).
It's a shame that this epitome in the Fighting genre has never being popular or understood by the American Crowd. This game is years ahead of his time.
The real problem is that the VF series had always required a great amount of compromise from the player, is not easy to get into and surely not the most friendly start, but if you can manage to learn and pull the basic mechanics, the rest is a piece of cake (and not just in VF but on any other fighting game, yeah!!! it's that Zen).
So if you are an average fighting game player, don't even bother, you'll end up writing a nonsense review as most of the GS members do, I'm saving some of your precious time. Go and play your easy to get into Tekken, Soul Calibur or DOA. I am going to pity your existence for the rest of my life.
If you are a true Fighting Game Fanatic, please do yourself a favor and get this game, if you have enough perseverance is going to change your life. And if you manage to master the game, you're going to experience some of the greatness that this game has to offer.