Newer cards with increased memory rely very little on AGP Aperture. Newer games rely on newer cards with more memory and don't make good use of AGP Aperture. So just get a good card.
3D Mark 2001 seems to have a preference towards 128MB AGP Aperture, but that's just an old benchmark, not a real game.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>