and it's easier to combine more then 2 cells that way.
Regardless I don't like the way either method handles blank cells so I use a borrowed UDF
Disagree on the first point. In what way is it easier? You have to put a comma in between each reference in CONCATENATE anyway, just sub in an ampersand and drop the CONCATENATE function.
And what's the issue with blank cells? A blank cell has the value "", which is what it puts in the cell value when you use either method. UDF's are always a last resort for me. They're notoriously inefficient relative to built in functions.