A number of reputable companies offer DNA tests for genealogical purposes. As a general rule, I recommend that anyone new to genetic genealogy test with AncestryDNA first. They have the largest database of DNA kits by far (see below) and also offer the most user-friendly tools for integrating DNA results with traditional genealogy.
For additional DNA matches, test with 23andMe. Their “Ancestry Service” test is fine for genealogical purposes, and health reports are available at additional cost. Another great option, especially if you have continental European ancestry, is MyHeritage. They have the third largest database overall and the most robust database for non-English-speaking countries in Europe. MyHeritage also has good tools to integrated DNA results with traditional genealogy.
You can also upload your AncestryDNA results to the smaller databases at FamilyTreeDNA and GEDmatch. Note that both companies sell access to law enforcement, who may not respect your privacy choices.
Based on my experience working with hundreds of people from different backgrounds, AncestryDNA and 23andMe have the most accurate ethnicity estimates.
Autosomal Testing Growth
Feel free to use the graph above in presentations to genealogy societies and DNA interest groups as long as you cite this webpage as your source. The chart only includes autosomal databases that offer relative matching and for which database size is available.