MyHeritage allows you to upload your autosomal DNA results from other companies. This is a currently a free service, but after 1 December 2018, advanced features will be paid. If you upload now, these services will remain free.
If you upload after 1 December 2018, you will still see your matches but you won’t be able to use the chromosome browser or see ethnicity predictions. The chromosome browser is particularly useful since you can then see if multiple people match each other on the same segment, indicating a shared ancestor.
MyHeritage supports uploads from Ancestry, FamilyTreeDNA, 23andMe, and LivingDNA. I recommend uploading FamilyTreeDNA results since they use the same lab as MyHeritage so the results are fully compatible. Uploading results from other companies may give more false matches and may miss some of the more distant matches.
MyHeritage is quite popular in the Netherlands so a great place to find DNA cousins. See Dutch DNA testing strategy for more information about finding Dutch DNA matches.