A vCard, .vcf or Versitcard is the standardised file format for electronic business cards. This is a universal format understood by most devices and software that handle things like contact information and email. vCards can hold everything from your first name, to a photo, to an audio clip. There is some good information about this format on Wikipedia.
meCARD is a more compact format, and that it generates a smaller QR code, meCARD might make more sense for contact information, it is possible that your phone will understand both formats, in which case meCARD would make more sense for contact information. as some phones like blackberry tends to face some problems scanning vCards.