Personally, I don't think the Reds have a rival.
From 1980-2004, the Reds have managed to make the playoffs twice, 1990 and 1995.
1990 NLCS 4-2
1990 WS 4-0 (may be awhile for another WS
1995 NLDS 3-0
1995 NLCS 0-4
The NL Central is one of the toughest divisions to win since it has the Cardinals, Astros, and Cubs so the drought may continue.