I voted for Marble Madness, but I dunno if my vote can be considered, as I only played 4 of those games.
I have never been a big fan of DotC. Could never figure out what makes it so special.
Neither I think Leaderboard is a very good game.
Silent Service, in the other hand, is lots of fun.
But Marble Madness is the real gem of those 4 games, and that's why it got my vote.