Which test should I take?
This is probably the hardest decision you are going to have to make and your main objective for taking the test will be what helps you make the decision. There are three main labs that perform tests. Each of them are very good and the level of testing is similar. However, some are more detailed, some focus on medical research, and still others primarily focus on genealogy. So let's look at the objectives.
For Medical Issues -
If you are primarily interested in medical reports, you should look at testing with 23AndMe.com or Geneticoncept.com.
The cost of the test is about $199.00 and provides a host of medical reports, and information about your genetic makeup like eye color, hereditary diseases, etc. The medical reports tell you whether you are at an increased risk for having certain conditions and diseases.
Was founded in 2014 and is a fairly new provider of tests for health and wellbeing. They offer two types of test kits, one for health and medical information and another for fitness. Their test kits can be purchased from the US and Canada, Europe, and the UK for $279 USD. For $96 USD, you can upload your raw data from 23andMe and have results in 6 to 12 hours.
Specializes in Chinese and Asian populations and also works with 23andMe. There is not a lot of documentation on the website as to how it works and exactly what types of tests it provides or for what price.
For Data Analysis - FamilyTreeDNA.com
Being a person who likes to crunch numbers and manipulate data, FTDNA provides the data to work with how ever you choose. Data from the other two labs is not available for you to download. FTDNA allows you to download detailed information about your chromosomes so that you can determine how each of your matches (and others) may be related to you. This can help you identify your MRCA (most recent common ancestor).
For Genealogy and finding relatives - All three
You can use any of the three labs to achieve this purpose. However, the fastest growing lab is AncestryDNA.com and the test currently costs $99. They have also started processing test kits overseas but matches are not currently included at this time from those test subjects. Down the road, they will more than likely combine them. You can search through your new matches and find relatives that are related to you and others and then work with family trees (if there are any) to determine how you may be related. They have a feature known as DNA Circles that helps you discover common ancestors. The other lab that is great for this is FamilyTreeDNA.com (FTDNA) also $99.00. This lab can provide you with the actual data on each chromosome that is used in processing matches to relatives. Additionally, they have more detailed tests for maternal and paternal (surname) DNA which can be used more extensibly. There are also surname project groups that you can join and work with others of the same name, location, or ethnicity. FTDNA also accepts test kits from all over the world so you are not limited to only American DNA test subjects. If you want the in depth data, this is the test for you.
Getting more bang for your buck
Since these tests can be expensive, it can be cost prohibitive for some people to take all three. FTDNA allows you to transfer your raw DNA data to them from AncestryDNA for about $40. which will save you about $60 in taking two tests. You first take the test at AncestryDNA and then when your results come back, transfer them to FTDNA. You get the benefit of both test banks full of matches.
Family test groups
If you have children and grandchildren, you should test them too. The reason being is that you inherit 50% of your DNA from each parent. Each of your children will inherit half of your DNA and half from their other parent, the same with grandchildren. But, the DNA that they inherit will not be exactly alike. If you were to look at the mtDNA (maternal) and Y-DNA (paternal) that each child gets, you could potentially map this DNA to create a phantom test subject to determine what one or both of your parents DNA should look like. Having more family members in a test group also helps to confirm family lines, especially when there are half siblings who do not share the same parents.
Why test with more than one lab?
Being adopted, I wanted medical reports and so I chose 23AndMe.com. Later, I also tested with FamilyTreeDNA.com and Ancestry.com just because they provided two more databases of test subjects that I could possibly connect with. Let me explain. On my test with Ancestry I found a 3rd cousin match. I contacted the cousin and got no response. Yes, there are some people who will not share information. Then I found another 3rd cousin match on 23andMe who was related to the cousin on Ancestry. By triangulating these two people and researching their family trees, I could identify the family line that produced my mother. Of course, this family had about 10 children and any one could be my great grandparent. About a year later a 1st/2nd cousin match appeared in my Ancestry results which descended from one of the 10 children mentioned above and confirmed that the grandmother of these other two matches had a sister who is my mother's grandparent. Had I not tested with both those labs, I would still be searching for that information. As far as which of the 10 children I come from, I can rule out one but as for the other nine, I may as well throw a dart. I can only hope that their descendants take a DNA test so that it sheds more light on the actual family line. Since that time, about 5 more tests have come in that are associated to the great grandparent above, solidifying my relationship to this family. So over time, the family lines will reveal themselves.
Links to Available Tests