Winamp, from a time when random meant random.
I've been on a road trip for the last week, and have well over 3000 songs on my "library" in Spotify. I was hearing repeats of songs within 3 hours (before my first fuel stop). When I hit random I expect each song in my Playlist to be put in a random order then navigated through. Spotify however creates a Playlist of a a subset of songs (this size has changed, at one point in time it was 20 tracks, but IIRC it's up to 50 now). As each plays, the last track in the Playlist is "randomly" chosen for that last spot with no context of recent listening history. And I seriously wouldn't doubt that there's a weighting due to popularity, your listening frequency, and several other factors due to some bean counters.
I miss using Winamp.