I would like to know which are the most popular DNA testing companies for these countries.
Have uploaded my data to a few sites but some don't accept uploads so could do another test if there is enough activity especially in Belgium.
I am Belgian of mixed European heritage. I tested with FamilyTreeDNA and transferred my data to MyHeritage. MH found more matches overall* but FTDNA found more closer matches.
• FamilyTreeDNA: 628 matches including 37 with over 50cM shared DNA
• MyHeritage: 2760* matches including 3 with over 50cM shared DNA
*Smallest shared DNA in FTDNA is around 20cM. In MH, it's 8cM. If I only count matches with over 20cM, the number of matches for MH drops to 450.
Due to the restrictions on transferring data, you're probably better off testing with 23andMe. But check first that the info is still accurate.