Playing Mishra's Factory in something like RDW might cost your good and average draws a small fraction of a % (total stab in the dark but we will call it 0.2%) in exchange for a slight improvement to your weaker draws
That being said, you might want to try some of these guidelines: If you enjoy controlling your opponents board and removing your opponents characters from play, the favourite cards are likely to be found in Ruby or Steel If you enjoy getting a lot of ink and resources, your best bet is Amethyst or Sapphire If you hate losing your characters or want to build your game plan around keeping specific characters in play, Amber or Sapphire will help you to do that
Generally, you don't want to pay more than one mana for a burn spell, especially one that's a sorcery, making Chain Lightning the perfect mana cost
Gold counterspells, provided they contained blue, where considered for the list and a couple were fairly close but didn't quite make it
Yargle, Glutton of Urborg is a vanilla creature, but that 9 power encourages you to go the Voltron commander route with your best equipment and auras
Cascade is formidable since it exiles cards from the top of your library until you exile a nonland card that costs less and lets you cast it for free
