None of the above.
You'll probably be complaining about the molasses performance of your Radeon 9700 before you'll notice the performance difference between AGP 4x and 8x.
Of all the factors I look at when shopping for a motherboard (stability, performance, price, overclocking and onboard features) AGP 8x is at the bottom of the list. And 8X is all those boards have going for them.
I'd recommend an Intel 845E or PE board. It only runs at AGP4X but has the best stability, reliability and overclocking performance of all the boards for the P4 Northwood.
If you have to have AGP 8X, wait for the launch of the Intel Granite Bay boards. According to some published rumors they will ship before Christmas, and will have Dual DDR and AGP 8X. Be warned that if you buy early you'll be a guinea pig for any initial release problems. But if you have to have the highest performing board, that is the one to get.
BHD