P35 without question. There are lots of good P35 based boards to chose from. Here are some top models that get most of the recommendations around here:
GIGABYTE GA-P35-DS3R: Awesome overclocking and BIOS support, great features, good cooling. An outstanding product.
GIGABYTE GA-P35-DS3L: Same thing as the DS3R, but without RAID support and slightly inferior cooling. I you don't want RAID then there's no need to spend the extra for the DS3R. This is the board I would get if I were building today.
ASUS P5K LGA 775 Intel P35: I'm not as familiar with the differences between the different P5K boards as I am the DS3 ones, but this looks like the standard model. A solid choice.
The DS3L is the best price/performance board out right now, and if you don't need RAID then it is the obvious choice in my opinion.