Formatting the return string

There are various ways in which you can format the return string.

Option 1: string interpolation

String interpolation was introduced in C# 6.0 and is the most idiomatic way to build up a string with one more variable parts.

$"One for {name}, one for me.";

Option 2: string concatenation

As there are few variable parts in the returned string (just one), regular string concatentation works well too:

"One for " + name + ", one for me.";

It is slightly more verbose than string interpolation, but still completely reasonable.

Option 3: using string.Format()

Before string interpolation was introduced in C# 6, string.Format() was the go-to option for dynamically formatting strings.

string.Format("One for {0}, one for me.", name);

String interpolation is in most ways superior to string.Format(), so it is no longer idiomatic to use string.Format().

Option 4: using string.Concat()

Another option is string.Concat():

string.Concat("One for ", name, ", one for me.");

Conclusion

String interpolation is the preferred and idiomatic way to format strings. String concatentation is absolutely a viable option too, as there is only one variable part. Both string.Format() and string.Concat() are functionally equivalent, but more cumbersome to read and there we don't recommend using them.