I love any kind of postcards, specially those with Arts, nature, old buildings, customs of your country, vintage, old commercials, quirky, funny cards. I'd really appreciate if you would draw something on the card. I generally prefer single image cards to multi image ones.
Or choose me a card at random - I'm sure I'll like it, especially if it says more than "Happy postcrossing" on the back ;-] The words on the back are as important to me as the picture on the front. I love reading either about the place where you live, or your life and what interests you.