I have to say I'm shocked that Codenames didn't win. I played Mombasa once and never saw it being played at public meetups, while I have seen Codenames at almost every public meetup since last Essen. Oh well, Mombasa is fun, too.
Mombasa is a very different game.
Codenames is less expensive (so more people are likely to have a copy), shorter (so it is more likely to fit into a game night), easier to set up, and simpler to teach. So it's unsurprising that it sees more play.