Either 1 will work just fine, I highly doubt the cpu will notice a 2 to 3 degree change from 1 or the other, I have both, and have found very little difference in temps. the temp of the actual water will be more of a factor then the material when not using a peltier.
Hoot is right, be sure to use all one type of metal in your system. He didn't say why, however. When you've got two different types of metal, IE copper and aluminum, connected by a fluid, corrosion takes place. There's an article on the main site about it - look under the watercooling section.