Sir; I am a Desktop Support Engineer in a company from last 3yrs and now i want to do global certi. which should select ComTia or Micro

Depending upon your personal interest you should choose the certifications. you can go for either ComTia or Microsoft but first of all you have to decide that on which path you want to go. If your basic knowledge is clear than you should go for Microsoft Certifications. And I believe the best is MCI