You know what, I've seen the light. Mono G clearly best control.
I love it. Control their life total down to 0, and they can't do **** about it!
On a more serious notion, I currently like URx the best for control colours. Magma Spray's exile clause has been very relevant to me (relevant enough that I'm running it as a 4-of over other 1-CMC removal), Radiant Flames >>>>> Languish currently because coming online a turn earlier is HUGE, and Harnessed Lightning is way easier to cast than Grasp while being about as good.
As for wincons: Chandra is about as good as Sorin (though I think she's positioned a bit better in the current meta) and while Jeskai loses out on Liliana and Ob, gaining Nahiri makes all up for it. With a wincon-suite of Nahiri, Disciple, big Jace, Chandra and Gearhulk, plus maybe baby Jace or Kefnet as well as two Pull from Tomorrow, I think Jeskai is set up well enough in that regard.
Compared to Jeskai, Grixis has to resort to Obi instead of Nahiri, which is shaky considering the manabase and thus slightly weaker. On the other hand, Grixis gains access to Fatal Push, making its aggro matchup even better (3 Push, 3 Lightning, 2 Spray, 2 Flames is fantastic). I think it's a tad too light on wincons, but playable.
Esper is still the best in control mirrors, but I found it weaker in aggro match-ups, and I think the difference is significant.