First one, hands down. Z68 is a superior chipset in most ways, and P67 should only be reserved for non primary PCs and mom's upgrade.
You'll thank yourself later for getting a Z68. The extra features are worth it.
The other reason the $114 board is less is also because it's an ECS, they tend to be a little bit cheaper (ECS has a bulk manufacturing model, more so than other vendors... it doesn't make them horrible, but just something to be aware of)