I use HTML and CSS to program my websites which usually don't get published to the web. I also use JavaScript sometimes so people don't copy the source code for my website.
Probably BASIC because as the name implies it is basic. I am starting on BASIC myself and I feel I made a good decision. If you are leaning towards web design though HTML is a must. Unless you are using a WYSIWYG HTML editor like FrontPage or something like that.