which one to use?

[kleinma]

I am doing some form validation and I simply want to check if a given text box was filled in.. doesnt matter with what.

simple enough, I know... but which one of these methods for doing so would you say is the best. or is it all just preference?

txtName1.Text = String.Empty
  txtName1.Text.Length = 0
  Len(txtName1.Text) = 0
  txtName1.Text = ""
  txtName1.Text.Equals(String.Empty)