in 99% increasing screensize will look better than increasing AA (within reason)
afterall AA is meant to lessen alaising which is caused by outputing to the computer/tv screen which has a limited resolution
What's the performance we see with 4xAA nowadays, 25%? Before someone pulls out benchmarks to prove me wrong, the no-AA and AA scores better both have AF enabled.
I seriously doubt increasing the screen resolution by a measly 15% in each direction (for an equivalent performance hit) will give you better images than 4x rotated grid AA. I'd bet 99% of people would agree in a side by side comparison in motion.