I first tested with 23andMe and the results included a Y haplogroup of R1b-L21 and mtDNA haplogroup of J1c3. I uploaded my data from 23andMe to GEDmatch, MyHeritage, FTDNA, Genomelink, WeGene, MyTrueAncestry and dna.jameslick.com. These uploads were all initially free, although I've since paid to upgrade at MyTrueAncestry and GEDmatch, and at WeGene uploads are no longer free. At dna.jameslick.com my estimated mtDNA haplogroup was deepened to J1c3b2.
I recently took the Big Y-700, and my terminal Y SNP is BY154246 (L21>DF13>DF21>DF25>DF5>FGC3899>FGC58919>BY154246). Big Y was worthwhile, because my matches have illuminated the history of my paternal line.
I also tested with AncestryDNA this year, and this was useful for my more recent genealogy. The ThruLines feature in particular has confirmed that the 16 grandparents of my grandparents were all indeed my biological ancestors, because of my multiple DNA matches with their cousins and other descendants. This might seem unsurprising, but I was surprised by the number of previously unsuspected adoptions and IVF sperm donor conceptions revealed by my DNA matches with previously unknown biological cousins.
For example, I discovered that my father had a half-sister he never knew about who was adopted by another family. She never knew that she was adopted, but her daughter has such a strong DNA match to me and other cousins that my paternal grandfather is the only plausible candidate for her biological father.