of the two id pick virtual fighter, its more fluid, more options, classier presentation, etc... it also most literally fits the term virtual; you can do almost anything you would do as a fighter. they even have designated moves to catch your opponents attack and use it against them, in more than from one angle. also if you wait till august, an uprgrade with two new characters will be realeased for less than 20 dollars. i actually have not had the priveledge of playing tekken 4 but by judging from the parts before it(if 4 is loyal to them); it seems too blocky, cumbersome, pseudo turn based. "you hit me than ill hit you"
i think you should consider dead or alive 2 hardcore. doa draws its fame from reasons other than being a good fighter. however it seems to me like its somehow the most feaseble presentation of humans fighting, it is also very smoth and fluent. even if its characters are shallow and cartoony. (++ its cheaper, and fun to look at)
other wise i havent had the priveldge of playing many fighting games as of late. the best fighting game ever is smash bros.