23andMe gives the most detailed ancestral testing. Ancestry.com is more popular, but 23andMe is more accurate. There's also a site where you can upload your results to connect and compare with others.

Some things to consider: a Y DNA test will give your father's line (your father, his father, his father, etc) and M DNA for your mother's. The general test that they use covers all lines, but is only accurate for about 5 generations. That can be useful but not as valuable. So for genealogical purposes I would get the Y DNA test.