Here we go :
1. Black :
I'd run Black in deck, all days, just for 3 cards :
Inquisition of Kozilek,
Thoughtseize and
Liliana of the Veil. All decks I make uses these cards, in many variants (Jund, Mardu, Abzan, Rakdos, 8-Rack, Black Devotion). I just like running discard, playing the mind game on what to discard to win the game at a proper moment, plus when I started Magic, I read something like "
Disrupt their hand, win the game", I kinda stuck to it
Black also offer some of the best target removals in the game.
2. Red :
I ran RDW for days, I liked it a lot just for the cost-efficiency aspect.
And come on, send me rocks if
Lightning Bolt isn't one of the best cards in Magic ?
I also like a lot the story of Chandra, that's help, and Red has more Dragons than other colors
3. White / Green :
I put them at equal, just because they synergize pretty well with either Red or Black (specially Green).
But I think I like White more than Green, just for the aspect of lifegain and White offers Angels, Angels are cool !
I also like the aim of Elspeth (specially Kinght-Errant), I always try to find a spot for her in my decks using White.
4. Blue :
I don't really like this color, maybe it's because I played too much against it, or it is just not my playstyle.
I'd rather ask myself : "What do I have to discard ?", than "Do I have to counter this ?"