from what i can tell, white has ondu cleric, which provides awesome life gain to help out early and late game, and has the best support, from kazandu blademaster, helping against aggro, and as a late gamer winner, not to mention a one drop ally, which is hard to find.
also, black has hagra diabolist, however, it's really the only black ally i like, however, sign in blood is nice, especially when counteracted by ondu cleric, as is doom blade, throat, despise, inquisition, and duress.
as good as those black options are, i feel like green is probably stronger, as it provides harabaz druid, beast within, and birds of paradise, as well as genesis wave. this will me have three ways to get out my black ally (hagra diabolist) as well as lets me run another color, in this case, blue for phrexian metamorph, to math their threats such as grave titan, as well as preordain, and lets me run the shapeshifter which is brutally good, as it can let me get a hard hitting attack, having 2 hagras, and lets me gain lie copying ondu cleric, as well as letting me get more mana with an extra harabaz for huge mana excelleration for a genesis wave, or another blocker from kazandu blademaster. blue also allows me to run spellskite, in order to protect my precious allies that have so much synergy, such as lots of having 2 ondu clerics out, or having 2 harabaz druid out on the field so that i can get out a massive genesis wave.
running 3, instead of 4, geneis wave ensures that i will be capable of getting them in hand, whilst also making sure that i have other things in hand before. Look at jwari shapeshifter for instance, the card is awesome and all, but he is very, very weak when i have 2 in my opening hand, along with a spellskite and a metamorph. running 3 of each of those also opens room up to let me run other nice things, such as into the roil (SB) and the awesome card advantage sphinx, not to mention it leaves open room for specific cards which can wreck me, such as the aforementioned into the roil, an awesome planeswalker fixer, (gideon + day combo wrecks this deck btw...)
sb looks like this:
we have tumble magnet to help against not only the day + gideon combo, but also the valakut matchup
we have spellskite to help against targeted black kill spells, as well as red burn that will be more than normal, and often sided in against me
we have into the roil against gideon matchups, as well as other things that might be a rough matchup, such as bouncing a tempered steel or something.
then we have negate against day, black sun, and planeswalkers, as well as against things like messing up a valakut's summoning trap, that they will side in expecting me to side in a leak, trick of the time, not to mention it's very viable in many other situtaions.
then we have gideon to help the