K240 and UFO were two of my favourite games. I think UFO was once rated the top PC game of all time. The interface is a little clunky by modern standards and the graphics blocky, but still one of the best games even today.
I enjoyed most games I played. You had to be picky when you were a kid with not much money, so we only got games with good reviews. The only games I remember were dull were Team Yankee, 688 Attack Sub (both part of a pack with F-15 Strike Eagle, which was excellent), and some crappy PD games.