Some of the best cards in the game only cost one Red mana, like Lightning Bolt or Ragavan, Nimble Pilferer
Theres also the 10 poison counters win condition, which started as an alternative win condition but can be considered a third way to win based on how much poison there is in competitive Magic
Greel, Mind Raker Greel, Mind Raker strikes me as the worst horror commander because its discard ability targets a single player, and thats ineffective in EDH
Even in a town deck I don't think it's a good idea to run this
Phyrexian Metamorph + Other Clones I'm ranking Phyrexian Metamorph here, but Im also including some permanent-copying clones as honorable mentions
Baron Rivalry (Deadly Dispute) Rating: 5/10 Deadly Dispute has become known as perhaps the best variant of the classic Village Rites card design, even to the point where it was banned in Pauper