ArgumentException or ArgumentNullException for string parameters?

I’d say the second way is indeed more precise – yes, it’s more cumbersome but you can always wrap it in a method to avoid having to do it all the time. It could even be an extension method:

str.ThrowIfNullOrEmpty("str");


public static void ThrowIfNullOrEmpty(this string value, string name)
{
    if (value == null)
    {
        throw new ArgumentNullException(name);
    }
    if (value == "")
    {
        throw new ArgumentException("Argument must not be the empty string.",
                                    name);
    }
}

Another form which is potentially useful is one which returns the original string if everything is okay. You could write something like this:

public Person(string name)
{
    this.name = name.CheckNotEmpty();
}

Another option to consider is using Code Contracts as an alternative to throwing your own exceptions.