For work/job interviews/professional functions I have two trusted Armani suits: A pant suit in black, and skirt one in brown tweed. They both have one button so it's flattering for a petite person. Thank God for these suits!
I'm much more capricious and impractical when it comes to going-out outfits, so I'm afraid there is no favorite or basic in this case. However, I do like to build an outfit around shoes. I don't think I own a lot of shoes so I would consider them basic enough? Like my fellow TFSer's, I am very fond of Manolo, Louboutin, Lanvin, Balenciaga, Marc Jacobs, and Prada. They are all in constant rotation so I assume they are the basics in my wardrobe?
Finally, I'm much more of a hopeless bum than I wish to sound!
Since this is a fashion forum I do feel the duty to speak more 'fashionably'. Most of the time (these days), I actually wear j-crew sweaters, yoga pants, and Uggs. Since I've been working from home, I am free to indulge in comfort. Oh, how I will miss these days when they come to end!