How to insert C# variable value in between string properly?

Here are the ways to insert C# variable in between a string:

1. Using string.Format
   

   var str="<span href='/ShowQuote/{0}?NewTab=True' style='margin: 10px; text-decoration:none' class='ShowQuoteClick'>Fetched one quote for {1} with Id-{2}</span>";
   var newStr=string.Format(str, QID,MainCompanyName,Id);?

2. Using C# 6.0 String Interpolation
   

   var QID= "1";
   var MainCompanyName = "Test";
   var Id="11";
   var str = $"<span href='/ShowQuote/{QID}?NewTab=True' style='margin: 10px; text-decoration:none' class='ShowQuoteClick'>Fetched one quote for {MainCompanyName} with Id-{Id}</span>";