Accurate field mapping is probably the most important thing when you want to migrate contacts cleanly. I have experimented with various converters, but the majority of them either do not recognize certain fields or put them in the incorrect vCard sections. The experience that I had with OSTtoPST CSV to VCF Converter was the best, chiefly because the mapping system is very transparent. You are allowed to determine the exact location of each CSV column in the VCF file. This guarantees that even nicknames, telephone numbers, email addresses, and any other custom fields will be preserved during CSV to VCF conversion. If you are planning to convert CSV to VCF and still want the formatting to remain, then it is absolutely necessary that you have control over mapping. This tool also works as a standard CSV to vCard Converter, which makes it easy to create well-structured vCard files for phones and cloud services.