I don't think I've had to worry about performance vs. quality in quite some time, but I'd have to say if anything, I prefer an equal balance between the two.
You don't need the highest Anti-Aliasing or Anisotropic settings, since really, as long as you've got 2x/4x on, it'll look fine enough. If you can pull off 8x/16x, then sure, go ahead. But you don't *need* it.
If you can splurge the extra money on a graphics card that can, without harming other funds you might need, then that quality is a nice bonus to go along with it.