I have the following two SQL select and they achieve the same result. I am wondering which one is better to use.

UPDATE Client SET [Geography]=geography::STPointFromText('POINT(' + CAST([Longitude] AS VARCHAR(20)) + ' ' + 
 CAST([Latitude] AS VARCHAR(20)) + ')',4326) WHERE Numero=1

UPDATE Clien SET [Geography]=geography::STPointFromText('POINT('+CONVERT(VARCHAR(20),Longitude)+' '+ 
 CONVERT(VARCHAR(20),Latitude)+')',4326) WHERE Numero=1

As you can see, one is using the CAST() syntax while the other one is using the CONVERT() syntax. My concerns are about the performance and the long time support of one or the other of those two functions.